The Frankish Empire fell apart after the death of Charlemagne. Between the 9th and 10th centuries, wars in France and Germany caused unrest and misanthropy among many people. At the same time, the economic power of the monasteries was growing, some of the monks had become as corrupt and degenerate as the secular founders, and the Benedictine monastic system was in a state of slackness, so the Clunian reform movement began to rise in the church, which led to a resurgence of monasticism. However, the Cluny reformers not only wanted to reform the monastic system, but also tried to use the economic power of the church to control the divisive and volatile political situation.

In 910 William the Pious built a monastery in Cluny, in eastern France, not far from Macken, which provided for the protection of the Pope only, from any other bishopric and secular power, and that its lands were inviolable from all encroachment. It required the monks to abide by the strict Benedictine rules of asceticism. The establishment of the Cluny Monastery caused great repercussions in the Church. Under the zeal of the first and second abbots Berno (910-927) and Otto (927-942), many monasteries followed suit and reformed, and a monastery of Santa Maria Maggiore, representing Clunian, was established on the hill of Aventine in Rome. By the middle of the 10th century, the Cluny movement had grown from France to Italy, Germany, England, Spain, and other places. These Cluny monasteries were all under the orders of the abbot of Cluny, and all the abbots of Cluny monasteries were also appointed by the abbot of Cluny, in fact, forming a system of Cluny monasteries headed by Cluny, which became a kind of sect. Religious and political forces.

As the Cluni faction grew in power, its reform goals were no longer limited to the reform of the monastic system. During the reign of Abbot Otiro (994-1048) of Cluny. In order to curb the armed conflicts that often took place between feudal lords, between monasteries and feudal lords, and between monasteries for economic gain, the slogan "God's truce" was proposed. It is stipulated that from Wednesday morning to Monday morning the Church will be commemorated with severe punishment for all acts of violence. But it didn't really happen. At the same time, the Cluny movement also generally opposed the corrupt behavior of the clergy, resolutely resisted the "Simonism" that was prevalent in the church at that time, which used money and other despicable means to obtain the clergy, and the "Nicholasm" that destroyed the celibate life of the clergy and justified the marriage of wives and concubines. In order not to weaken the power of the church. Through these reforms, the Clunians sought to raise the status of the Church and strengthen its power in the struggle for power with secular rulers.

At the beginning of the Cluny movement, most people were not opposed to the appointment of clergy, but by the middle of the 11th century, the Clunians saw the appointment of the clergy as buying and selling the clergy as much as the laity, believing that the king had usurped the right to ornate the clergy, and tried to regain the right to reclaim the right to reclaim the right to increase the power of the pope. However, during the reign of the Holy Roman Emperor Henry III (r. 1039-1056). His control over the elective pope was at its peak. For a long time, the selection of the pope was controlled by the princes, and in the first half of the 11th century, there were three Roman popes. In 1046, Henry III led an army into Rome. Three popes were deposed at once, but the two popes were poisoned one after the other, and finally a Cluny clergy was appointed to the papal throne. Named Leo IX (r. 1049-1054), the reformers seized real power in the papacy. Leo IX vigorously promoted the Cluny reform. A major reorganization of the Cardinal Order, the direct adviser to the Pope, removed the Romans who did not sympathize with the reforms. A group of Cluni cronies were appointed from other Western countries, and among them were three very important and influential figures: Holmbert, the white Hugh Ge, and Hildebrand. However, Leo IX's series of reforms did not materialize in Rome, and after his death, the successor pope continued the ideas of his predecessor. After the death of Henry III in 1056 and the succession of Henry IV at the age of four, the reformers took the opportunity to launch a movement to free the church from the control of the imperial power, which was the famous "bishopric election" in the Middle Ages, in which Hildebrand was the most powerful leader and doer.

At the same time that the Byzantine Empire was in external trouble, it was also experiencing a great storm within the empire caused by the papal peasants. With the successive defeats of the empire in war and the loss of large swaths of territory, on the one hand, military expenditures rose sharply, the treasury was empty, and the state levied more and more taxes on the vast number of free peasants under various names, so that the masses could not bear the heavy burden. On the other hand, the military aristocracy, the imperial family, and the emperor indulged in hedonistic corruption, and the wealth of the Church was rewarded by the emperor and donated by others, and by cunning and plunder, and by a large number of dependent peasant contributions, the land alone, the Eastern Church already occupied one-third of the country's land, so that the life of the clergy and the upper class of the monasteries in the church was also very corrupt and luxurious, and the emperor and some of the great nobles coveted the property of the church because of the lack of payment. Against this social background, at the beginning of the 8th century, the Papalines rose up against the orthodox Church, which defended the existing social system, and demanded the simplification of the church. The rituals, the abandonment of luxury, the abolition of icon worship, the abolition of the church's hierarchy and monastic system, reflected the change of the oppressed to secular and resectant. The desire to teach an irrational state. These ideas quickly gained widespread support, and peasants and urban commoners in Asia Minor defected from the Orthodox Church and demanded the abolition of icon worship. As a result, the broad masses of Paulicians took advantage of the siege of Constantinople by the Muslims to launch a large-scale campaign of iconoclasm.

In the 4th century, due to the conversion of a large number of pagans to the Holy See, the worship of icons, relics and holy places became popular. Emperor Constantine the Great advocated the worship of holy relics, and later in the Eastern Church, which was deeply influenced by Greek culture, icon worship became more and more popular, and even became a means of accumulating wealth. In the 8th century, monasteries spread throughout the empire, with a large amount of land and property, and privileges such as tax exemption and non-military service, which directly affected the economic income of the empire. In this situation. The powerful emperor Leo III (717-740) tried to rule the Church in the spirit of Justinian and control its wealth. to strengthen the centralization of the empire. Therefore, he used, supported and enforced this campaign against icon worship. The military aristocracy also threw themselves into this sabotage campaign. In 726, Leo III decreed that all icons and relics in churches and convents should be abolished, nationalized, and painted on the walls. Religious rebellion. The emperor sent troops to enforce the edict abolishing the icon, and suppressed the rebellion. In response, Pope Gregory III (r. 731-741) convened a council in Rome in 731 to excommunicate all opponents of icon worship and to stop paying tribute to the Byzantine treasury. Leo III retaliated by taking all of Sicily and southern Italy out of the papal domain. Constantine V (r. 741-775) further pursued the policy of iconoclasm, and in 754 he presided over the convening of the Church of Constantinople. Teach the conference. The cult of icons was declared to be idol worship, and the icons were forcibly abolished, so that many monasteries were turned into barracks, a large number of monks were forced to return to the laity, and a large amount of religious property was nationalized. He also excommunicated John of Damascus, the most influential figure in the worship of icons, from the Holy See and pushed the iconoclasm movement to a higher level. Tide. The above-mentioned series of measures effectively dealt a blow to the excessively inflated power of the Church and strengthened the political and economic power of the military aristocracy.

In 780, the young Constantine VI ascended the throne and the Empress Dowager Irene (r. 780-802) became regent, and the policy of the empire changed. She opposed iconoclasm and convened the 7th Synod in Nicaea in 787, which was also attended by the Pope. The council condemned the Constantinople sect in 754. The synod was blasphemous and heretical, ordering the restoration of the icon. At this meeting, the divinity could not leave the material world. The idea that the material world could be an intermediary in approaching God triumphed. However, the Conference did not restore or return all closed monasteries and ecclesiastical properties, nor did it avoid the question of the ownership of Sicily and southern Italy. At the same time, since Irene did not recognize the coronation of Charlemagne, Emperor of the Frankish Empire, in 800. Therefore, the Pope sent envoys to attend the meeting. However, reservations were expressed regarding the resolution. After the deposition of Irene in 802, the problem of icon worship was reversed several times. After more than 100 years of controversy over icon worship. It ended with the so-called "complete victory of the idols". Throughout the struggle, the Roman Church was always on the side of icon worship.

In the course of the controversy over the worship of icons, there is a figure and a historical fact worth mentioning, and that is the "carol" creation of John of Damascus (c. 700-753) and the Holy See in Muslim-occupied areas. John of Damascus has always been a passionate proponent of icon worship, and he justified icon worship from the point of view of church theory. If it is accepted that the church as the incarnate man has an image, then the worship of the image of the church is the same as the worship of the Gospels, if it is recognized that the humanity and divinity of the church are united in one person. The Gospels depict the image of the church in words, while iconography is nothing more than painting to depict the image of the church. He was excommunicated from the church by Constantine V for this. In the occupied territories, due to the practice of Muslims. Teach a policy of tolerance, so in the church in Jerusalem the morning prayer rites began to replace scriptural hymns with "carols", of which John of Damascus and Cosmas the musician were the most famous authors. Throughout the 8th century, the Muslim-occupied regions of Antioch and Asia Minor flourished in the creation of carols, and after the 7th Council Constantinople became the center of composition.

Due to the differences in geography, politics, and especially cultural traditions, the Eastern and Western churches gradually formed two factions in the course of history, and the two factions have been in constant conflict over the supremacy of the church for a long time, which deepened the rift between the two sides again and again, and finally led to a complete rupture between the two sides in 1054.

Since the Synod of Nicaea in 325 AD, the disputes and hatreds between the Eastern and Western factions, although in different forms, have always revolved around a central question: "Who is the head of the Holy See?" The Council of Charcedon in 451 proposed that the bishop of Constantinople have the same status as the bishop of Rome, but the Church of Rome rejected this. For a long time, the Church of Rome considered itself to be the creation of the saint Peter, and asserted itself as orthodox, and put forward the "doctrine of Peter superiority" to argue that the Bishop of Rome was the natural leader of the universal Church. In 482, the "Akaciu Division" was caused by the Henoken Edict, and the East and West were cut off for 36 years. At the end of the 6th century, Pope Gregory I of Rome took over the city of Rome and stood up to secular monarchs, respecting himself as "the servant of God." above the bishops. In 726, the Eastern Roman Emperor Leo III launched a campaign of iconoclasm, which the Pope firmly opposed. And in turn to support the enemies of the emperor. For this, the emperor deprived the papacy of jurisdiction over southern Italy and Sicily. led to a break between the pope and the emperor, who instead sought the support of the Franks. In the 9th century, the Western Church forged the Church of Isidore and made various demands on the Eastern Church. The two factions in the East and the West condemned each other and attacked each other in the dispute over the "Hezi" sentence, which made the contradiction even more acute.

Around the question of the patriarch of Constantinople, there was another fierce scuffle between the East and the West. In 842, the young Byzantine Emperor Michel III (r. 842-867) ascended the throne, and the Empress Dowager Theodora became regent. In order to break free from his mother's control, the emperor who grew up deposed Ignatius, the patriarch of Constantinople appointed by his mother, in 858 and appointed the laity Phoetius. In order to legitimize the patriarchal status of the Buddha Tius, who had no divine qualities. Michel III wrote a letter inviting Pope Nicholas I to send an envoy to the Sect. Teach the conference. In 861, papal leates attended the council with a letter from the pope himself. In his letter, the Pope reaffirmed the papacy's position at the head of the entire Congregation and made the return of the dioceses of Sicily a condition for agreeing to the legitimacy of Photius as Patriarch of Constantinople. After the meeting, the pope found that the Byzantine Empire had no intention of returning Sicily and other dioceses, so he convened the Patriarchate in 863. The synod retaliated by excommunicating Photius and recognizing Ignatius as Patriarch of Constantinople. The East and West sides play with each other, intrigue and flip. Cloud cover. The rain made the struggle more and more intense.

For the control of the new dioceses of Moravia and Bulgaria. The struggle between the Eastern and Western factions was fought for a long time, and the struggle also reached a fever pitch during this period. The Moravian monarch wanted the support of the Byzantine Empire to resist the invasion of the German feudal lords and ecclesiastical powers, and the Byzantine Empire could not ask for it. Since the loss of the three dioceses of Antioch, Alexandria, and Jerusalem. The Byzantine Empire tried to develop its own power in the Balkans to the west. Therefore, in 863 two brothers, the monks Cyril and Methodius, were sent to preach, and they were based on the Greek alphabet. The Slavic alphabet was created, and missionary books were translated into Slavic. It had a profound impact on the missionary cause of the time and the development of local Slavic culture. To this end, the German feudal lords orchestrated a coup d'état in 870. The Moravian pro-Byzantine monarch was overthrown, the missionaries of the Byzantine Empire were imprisoned and then expelled, and the Moravian Church was controlled by the German Church. The struggle for spheres of influence ended in a victory for the Westerners, followed by a fierce conflict over the Bulgarian state.

The Byzantine Empire used both "peace" and force to get the Bulgarian state to recognize the suzerainty of the Byzantine Empire. King Boris of Bulgaria at that time also wanted to use the Holy See to unify the tribes, so he ordered the whole country to be converted to the Holy See. But the Byzantine Empire's demands for an inch of progress prompted Bulgarian state-owned enterprises to try to break free from its control. The Pope, who had been spying on the developments, took the opportunity to start the rebellion. In 866, King Boris, freed himself from the control of the Byzantine Empire and the Eastern Church, decided to recognize the supremacy of the Pope in the Holy See. The Patriarch of Constantinople, Phettius (810-8.95), was furious and immediately accused the Roman Church of six heretical crimes, such as the addition of the phrase "Wazi" to the Creed, fasting on Saturdays, drinking milk, eating cream and cheese during Lent, requiring celibate for clergy, and allowing only bishops to perform confirmation. In 867 the Byzantine Emperor Michel III, at the instigation of Fotius, convened the Patriarch of Constantinople. The synod excommunicated Pope Nicholas I (r. 858-867). In 868 Photius was removed from the post of patriarch by the new emperor Basel I, and Ignatius (799-877) was reappointed as patriarch. Pope John VIII threatened him to place the Bulgarian Church under the jurisdiction of the Church of Rome or remove him from the Patriarchate. Ignatius categorically refused, with the support of the emperor, and the contradiction between the East and the West became even more acute. In 870, the Pope rejected the request of the Bulgarian king Boris to set up an archcathedral in Bulgaria, which caused Boris to sever ties with the Western Church and restore relations with the Byzantine Empire. In 877 Ignatius died, and Photius was reappointed Patriarch of the Church of Constantinople. The Pope took the opportunity to make another request to the Bulgarian Church, which was rejected by the Byzantine Emperor and Photius. Thus the Roman Church cursed Photius again in 881. In 884, Simeon, the son of Boris who was a monk in the Church of Constantinople, ascended the throne and spread the organization of the Eastern Church throughout the country. After several battles between the eastern and western factions, the eastern faction finally ended in victory. At this point, the rift between the two factions could not be bridged.

11th century. The Pope united the Normans and Germans and introduced the Normans into southern Italy. An attempt to squeeze out the power of the Byzantine Empire in this region. He appointed a Roman priest as bishop of Sicily in southern Italy and instigated the Normans to prohibit the Eastern diocese from practicing Greek rites. Patriarch of Constantinople Patriarch Michel. Serularius (1043-1058 in office) was furious. On the one hand, he also sent bishops there to confront him, ordering all the churches that practiced Latin rites in the Byzantine Empire to adopt Greek rites; On the other hand, in 1053 he wrote to Pope Leo IX of Rome, condemning the heresy of the Roman Church, such as the consumption of unleavened bread in the Eucharist, the eating of animal blood, and so on. The Pope wrote a letter in response, accusing the Patriarch of Constantinople of the title of "Ecumenical Patriarch" and of treating the Western Church in the Byzantine Empire, re-emphasizing the supremacy of the Roman Church and its bishops over all churches and their bishops. In 1054, Pope Leo IX sent two envoys, Holmbert and Friedrich of Lorraine, to Constantinople with letters. Serularius refused. The envoy then placed the "Papal Encyclical" of the excommunication of Selularius on the altar of the Cathedral of Sophia as a sign of the rupture. Serularius immediately convened the sect. The Synod fought back, declaring the Pope and his envoys blasphemous. They came from the dark West like wild boars to the Holy City to slander the truth and dismiss Leo IX. At this point, the Eastern and Western factions of the Holy See finally officially split completely.

Shortly after the split between the Eastern and Western churches in 1054, Pope Leo IX died. In 1056 the Holy Roman Emperor Henry III died, and the younger Henry IV ascended the throne, with his mother Agnes as regent. The Clunes took the opportunity to start a movement to free the Church from the control of the imperial power, and the clerical and royal powers engaged in a contest over the question of the right to appoint bishops.

In 1057, Pope Stephen IX ascended the throne (reigned 1057-1058) and supported Cardinal Holmbert's essay "Three Books Against the Buying and Selling of the Clergy", declaring that the ordained priesthood ordained by the laity was invalid. In fact, it was a denial that the emperor had the right to appoint priesthood. Unexpectedly, the pope's sudden death caused a crisis. Hildebrand, the presiding officer of the Roman Church, turned the tide and convened the Council of the Reformed Cardinals of Cluny under his direction and planning. Elected Bishop Gerhard of Florence as Pope, named Nicholas II (r. 1058-1061). In order to free himself from the control of the Kaiser and the Roman aristocracy, Nicholas II followed the strategy of Hildebrand. Ally with the Normans in southern Italy and gain the support of the most powerful feudal lords in northern Italy. Then he went head-to-head with the Kaiser. In 1059, Nicholas II convened a council in Rome and promulgated the law on the election of the popes, drafted by Holmbert. It was expressly forbidden for the laity to be ordained, and that the pope could only be elected by the College of Cardinals, and that the choice of pope was not necessarily limited to the clergy of the city of Rome, and in exceptional circumstances, the place of election was not necessarily limited to Rome. Council on the Emperor and Secular Government. The role of power in the election of the pope is not mentioned, and in effect it is tantamount to a denial of their power. The papal election statute has been amended, but it is still one of the oldest statutes still in use today. Just as the provisions of the new law were in effect, the Pope died in 1061, as did the reformist theorist and cardinal Holmbert. Under Hildebrand, Alexander II (r. 1061-1073) succeeded him as pope. He continued to expand the power of the pope, forcing the archbishops who bought and sold the priesthood to be tormented, interfering in the marriage of Kaiser Henry IV, opposing Henry IV's appointment of the Archbishop of Milan, and excommunicating several of Henry IV's cronies.

In 1073, at the funeral of Pope Alexander II, the reformist leader Hildebrand was carried like a riot to the papal throne in the "Church of St. Peter in Chains" and proclaimed himself pope Gregory VII (r. 1073-1085). He devoted his life to the goal of "the supremacy of the church over the imperial power". Before becoming pope, he successively held important positions in the Holy See, became the behind-the-scenes presiding officer of the Roman Church, and made great contributions with his talent and strategy. The appointment of Pope came at a time when Henry IV was too busy suppressing peasant uprisings and noble rebellions in the country to take care of anything else, so Gregory VII took the opportunity to force him to repent to Pope Alexander II in front of the papal legate at Nuremberg and promise to obey the pope in the future. In 1075 Gregory VII convened the Roman Sect. The Synod issued the Papal Edict, reaffirming the prohibition of the ordination of the laity. Declare that only the pope has the ability to appoint and dismiss bishops, and make new laws. With the power to establish new dioceses, only the bishop of Rome can be called a universal bishop. The right to depose the emperor, the Roman Church will never make mistakes, the pope will never be judged, etc. In 1075, when Henry IV resolved the civil crisis, he quickly changed his attitude towards the Pope, objected to the Papal Edict and reappointed the Archbishop of Milan. Taking advantage of the opposition of thousands of bishops and priests in France and Germany against the ban on the sale of priesthood and priests' marriages, he convened a council at Worms on January 24, 1076, in which he violently rebuked Gregory VII and denied him papal powers. Cardinal "Hugh the White" took the lead in indicting the Pope for his crimes. All the bishops of Lombardy followed suit against him

Gregory VII fought back. On February 22, 1076 he convened a convening. The Synod, which issued the most famous papal decree of the Middle Ages, declared the excommunication of Henry IV, the abolition of his dominion in Germany and Italy, and the removal of the oath of allegiance from his subjects, which was an unprecedented demonstration of papal authority. In response, Henry IV wrote a sharply worded letter, declaring that the Pope was a pseudo-friar and should be removed from the papal throne and cursed forever. But Henry IV did not have the backing of a unified Germany. The German aristocracy and most of the monks took the opportunity to rise up against him. In October 1076, the German aristocracy convened a general assembly in Tribul, announcing that Henry IV would be deposed if his canonship was not restored within one year, and decided to hold a meeting in Augsburg in February 1077 to discuss German politics and patriarchy with the Pope. Teach the problem. Henry IV was in great danger. Faced with strong opposition, he was forced to beg Gregory VII in humiliation to help him break free from his predicament and revoke the expulsion. The Pope rejected all demands. Insisting on resolving these issues at the Augsburg Conference, Henry IV was cornered and decided to obtain the Pope's dismissal by means of forbearance. In order to be able to see the Pope before he attended the Council of Augsburg. In the middle of winter in 1076, he crossed the Alps. Wait in northern Italy, where the Pope must pass on his way to Germany. Gregory VII did not know the Kaiser's intentions, so he hurriedly took refuge in the city of Canossa. Henry IV waited barefoot outside the castle for three days, begging for forgiveness, and finally received a papal desolation on January 28, 1077, and then returned to Germany. This incident is known in history as the "Canossa Incident".

Henry IV was able to retain the throne by obtaining the papal edict through bitter ploy, which was tantamount to a return to the pope. After Henry IV returned home, he tried to stabilize the political situation and regathered the power of the princes and bishops who supported him, and those who opposed him greatly reduced their trust in the pope, and they all joined him in horror, and some nobles and bishops who insisted on deposing him elected Duke Rudolph as emperor. Gregory VII convened the Roman Sect in March 1080. The Synod of the Church once again abolished Henry IV's membership and throne. However, the reinvigorated Henry IV confronted it and convened a meeting at Blickson in June of the same year. The synod deposed Gregory VII and elected his archbishop Wilbert of the diocese of Ravenna as the pope, calling Clement III (r. 1080-1100), forming a situation of confrontation between the two popes in the city of Rome. Rudolf was killed in October, and Henry IV's position was more secure than ever. Determined to get rid of Gregory VII, he led an army into Italy in 1081 and laid siege to Rome for two years. Gregory VII was forced to call the Normans for help, but before reinforcements arrived, the city of Rome had been breached. Pope Clement III crowned Henry IV at St. Peter's Basilica. In May, Norman troops entered Rome and the Germans retreated north.

In 1099, Pascal II (r. 1099-1118) succeeded him as pope, and he had a sharp conflict with Henry V over the right to re-episcopy. In 1110 Henry V marched into Rome and forced the pope to back down. In 1111, an agreement was reached whereby the emperor renounced the right to appoint bishops, the pope renounced political and economic rights, and then the pope crowned Henry V. This agreement was fiercely opposed by the German bishops, who refused to surrender their political and economic privileges. The Pope was forced to revoke the agreement, and the Kaiser was furious and ordered the Pope and Cardinals to be imprisoned, forced to crown him, and surrender the scepter and ordination, which symbolized the power to confer priesthood. However, the Pope, under the angry protests and strong pressure of Cluny's reformers, convened the Patriarchal Council of Rome in March 1112. Teach the assembly, withdraw the agreement. In September again in Vienna Zong. The synod excommunicated Henry V and reaffirmed the lack of authority for the laity. In response, Henry V again led his army into Rome, expelled Pope Pascal II, and appointed Calixtos II (r. 1119-1124) as pope.

The long-standing struggle between the emperor and the pope for the right to appoint bishops gradually became aware of both sides. If it continues, not only will no one be able to achieve absolute victory, but it will also have a detrimental effect on their respective rule. At the same time, the results of the Crusades also made the two sides unwilling to fight again. And turned his gaze to the rich East. Some church leaders have also written articles arguing that both the church and the state have the right to appoint ordained people, and the state confers secular power. The Church confers the Sect. Teach power. This principle has already begun to be implemented in the United Kingdom. Thus, in 1122 Henry V and Pope Calixestus II finally reached a compromise and signed a contract with Wormsz. Religious agreement. According to the agreement, the bishops and abbots of Germany were elected by the clergy in accordance with the statutes, and the emperor could supervise the election on the spot, and in case of disputes, the emperor could negotiate with the provincial metropolitan and other bishops. The Emperor relinquished the right to appoint bishops and surrendered the scepter and the ring. The pope, on the other hand, recognized the temporal authority of the emperor. As a practical result, the appointment of bishops and abbots in Germany was only valid with the approval of both the emperor and the church. In other areas, the emperor's authority to appoint was largely collapsed. ‘

In 1198, Pope Innocent III (r. 1198-1216) ascended the throne and put forward the highest secular goal of successive popes, "the pope is the father of the world", and with the Crusades, pushed the power of the pope to the peak of development. Within the Church, Innocent III was in full compliance with the dictatorship. The idea of centralizing the power of the emperor in handling the affairs of the church. He believed that the bishop's duty was to assist the pope in administering the church. Faced with the inability of the conflicting secular monarchs of Western Europe to deal with the situation of the pope during the Crusades, he took over the power and appointed and dismissed bishops and abbots as he pleased. In relation to the imperial power, Innocent III based on the coronation of Charlemagne by Leo III in 800 AD. Insist that the pope has the right to decide who the emperor and king will be. He declared that the reference to the pope as "the successor of the apostle Peter" did not indicate the true status of the pope, who should be "the true agent of God."

Papal power comes directly from God, and all secular kings should be subservient to the pope, firmly preaching the idea of the supremacy of papal power. With this notion in mind. He instigated the Crusaders to capture Constantinople and establish a Crusader kingdom from the Balkans to Asia Minor. In dealing with Western European affairs, when Kaiser Henry VI died. The aristocracy fought for the throne and threw the political situation in Germany into chaos. Innocent III took the opportunity to provoke a civil war and profit from it. When Otto IV ascended to the throne in 1209 by the coronation of the Pope. The Pope did not hesitate to depose Otto IV and appoint Frederick II (r. 1212-1250) as Emperor of Germany in 1212, leaving German politics entirely in the hands of Innocent III. Taking advantage of this opportunity, he further expanded the power of the pope and intervened in the internal affairs of Western Europe, forcing King Philip II of France, King Altheus IX of León, King Sancho I of Portugal, and King Radislav of Poland to submit one after another. When King John of England rejected the papal appointment of Stephen. When Langton became Archbishop of Canterbury, Innocent III deposed the King and threatened to organize a crusade. The King of England was forced to submit, considered himself a vassal of the Pope, and agreed to pay an annual tribute to the Pope. With the submission of the English king, the power of the pope reached its peak.

Innocent III also organized several crusades against Byzantium, defeated the Orthodox Church, suppressed the heretical Albigensians in southern France, and invaded the Slavs on the Baltic coast. The papal power expanded, imposing a wide variety of ecclesiastical taxes on the peoples of all countries, and began to sell indulgences in large quantities, so that a large amount of wealth continued to flow into Rome. In addition, Innocent III actively supported the establishment and development of the Dervishes, preached the "Gospel of Poverty", tried to overcome the decadent tendencies that had grown in the Church, dismantled the heretical movement, and spiritually relieved the people of discontent with the Church. In order to consolidate the authority of the Roman Church, Innocent III also revised the canon code.

In 1216, Innocent III died, and Pope Honorius III (r. 1216-1227) ascended the throne. In 1220, Frederick II was crowned emperor by the pope, and he made every effort to establish a centralized power, suppress the rebellion of the feudal lords in northern Italy, weaken the power of the nobility and the church, and cause a joint rebellion of the nobility and the pope in northern Italy. This was followed by a long struggle between two popes, Gregory IX (r. 1227-1241) and Innocent IV (r. 1243-1254), and Frederick II. In 1243, Pope Innocent IV failed in his crusade against Frederick II and fled to France, relying on the French king to re-establish the Holy See. In 1248, Frederick II was defeated by a coalition of Italian cities and died two years later. From then on, the German Hohenstaufen dynasty declined, and Germany was divided into many separate feudal princely domains. From the middle of the 11th century to the first half of the 13th century, 200 years of secular warfare led to a major victory for the church over the imperial power, which was brought to the top by Innocent III. However, from the middle of the 13th century, when Innocent IV relied on the French king to rebuild the Holy See, the pope began to gradually fall into the hands of the French king, and the power of the pope began to decline step by step.

After entering the 11th century, the people of Western Europe were generally in a miserable situation, the vast majority of peasants became serfs, all kinds of taxes and forced labor were increasing, feudal exploitation and oppression were becoming more and more serious, coupled with successive famine years, the life of serfs was even more miserable. They have a strong desire to get rid of hardship and burdens. As far as the ruling class was concerned, the land of Western Europe had been carved up by the feudal lords, and in order to satisfy the growing desire for life, the feudal lords were eager to expand outward and create other sources of wealth in addition to increasing the burden on the peasants. The successive wars of annexation between the ruling groups made some people stronger and stronger, while others gradually declined, and the declining feudal lords also tried to find a way out. Moreover, the primogeniture system was widely practiced in Western European countries at that time, and the sons had almost nothing except the eldest son, so that a knightly class with no property and a desire for property, land and serfs was formed within the ruling group. These armed knights made their fortune by the sword, and they were either armed servants of the great feudal lords, or they robbed houses, so they also hoped to open up a way out of life. With the rise of cities in Western Europe and the development of trade, a large number of valuable goods from the East began to be shipped to Western Europe through Italy, which not only greatly stimulated the materialistic desires of the feudal aristocracy, but also found hope for land and wealth from the East. All of these conditions became the social, secular or economic material causes of the Crusades. Therefore, in the context of a society in which serfs were eager to be relieved of their misery and the feudal aristocracy was eager to acquire wealth, when the Church announced that the indebted peasants and the urban poor who participated in the Crusades would be exempt from paying interest on their debts, that they would be exempt from paying taxes if they went on expeditions for more than one year, and that serf expeditions would gain personal freedom, calling for people to march to the rich East, the Crusades became a way out of their predicaments and received an enthusiastic response. (To be continued......)