On March 6 of the first year of Eiroku, Nirayama Castle, the strongest castle in Izu, was conquered by the Takeda army, and the defender Masanobu Oto and others either committed suicide or were taken for it. Subsequently, the castles in various parts of Izu surrendered or were lost one after another. Takeda Shingen is not in a hurry to divide the troops into two ways, he wants to pacify the counties in Izu first and then send troops to Sagami, if the conditions allow, he can meet with the Asada for a tea or something.

Kimisawa-gun and Takata-gun were the first to be conquered by the Takeda Army, and the road from Izu to Sagami was blocked. After Tsunayo Castle and Atami Castle were captured by the Takeda Army, Naito Masatyo was sent to Atami Castle to garrison, the purpose of which was to prevent the remnants of the Hojo Army from breaking through to Sagami.

Although the Takeda Army was able to block the land routes, it was impossible to completely block the water routes. Because of this, Takeda Shingen ordered Yamamoto Kansuke to go and transfer more Hojo family retainers or wealthy families.

Of course, in addition to the leader of the Sagami Uraga Naval Army, Aisu Shosuke, there were also people in the Izu Naval Army who wanted to join the Takeda family, such as Yamamoto Masano, Yamamoto Ieji and others.

However, even the Takeda army is unrivaled everywhere it goes. There are still Hojo family retainers who are willing to give their lives for the main family.

After learning of the loss of Nirayama Castle and the loyalty of Masanobu Oto and others to the Hojo family, Mamiya Yoshiko and Nobutada Mazumi immediately summoned men between the ages of 14 and 65 to enter Kawazu Castle to garrison. Kawazu Castle is located in the northern part of Shimoda Castle, an important town in Izu, and if Kawazu Castle is lost, then Kamo will no longer have the strength to resist. No matter how enthusiastic the two of them were in guarding Kawazu Castle, the defenders in the city, including the peasant soldiers, were only 600 people.

Therefore, the Hojo clan also led a thousand reinforcements from Shimoda Port from the waterway with Kojima Saemon Taro (Sagami, Sagari Sakura), who was originally only an acting official, and Igami Kokusuke and Ryo Iba. Shimoda Castle was garrisoned by Yasunobu Ita, a member of the Appraisal Clan, Fukone Castle between Kawazu Castle and Shimoda Castle was garrisoned by Suwa Umasuke, and Yazaki Castle on the western coast of Shimoda Castle was garrisoned by Nanjo Tsunashi (Odawara Castle). Yasuhide Shimizu, the lord of Shimoda Castle, was in the Izu Islands to mobilize naval forces and supplies, ready to support the Hojo Army in Minami Izu at any time.

The Hojo clan has the heart to guard Izu, but the strength of the Hojo family is not as strong as it was ten years ago. The undercurrent under the calm of the Boso Peninsula, which had not been conquered for a long time, was no longer something that the Hojo family could quell. This is exactly what the saying is: "If you have the intention to kill a thief, you have no power to return to heaven." ”

Seeing that the Hojo family's control over the Boso Peninsula was getting lower and lower, Satomi retainers such as Wada Shinsuke, Kiso Shobei, and Satomi Satomoto, who were still in the Uesugi domain, actively contacted the former Satomi family retainers such as Ichikawa Gentosai and Okamoto Yorimoto. Since the death of Satomi Yoshiyao and Satomi Yoshihiro in battle, the Satomi retainers who had not yet been poisoned by the Hojo family have been hiding in reliable villages, and they are waiting for the day when the Satomi family will resume their family name. Even Hideji Kano, who is in Kitakami Tsuki, is one of the people who Satomi contacts his former ministers. The former retainers of the Satomi family want the assistance of the Uesugi family the most, and only then can the Satomi family quickly restore the name of the family.

In just two days, the 20,000-strong army of the Takeda Army quickly moved south to the outside of Kawazu Castle. As the partial division of the Takeda Army, Takeda Nobuyoshi and Baba Nobubo conquered the branch castles of Hojo one by one. Takeda Nobuyoshi conquered the Atagawakan northeast of Kawazu Castle and captured the defender Kida Mi Katsumasa. Baba Nobubo conquered the cities of Tohi, Anrasa, and Matsuzaki on the southwest coast of Izu one after another.

The Hojo Army, which was entrenched in Shimoda, Kawazu, Fukone, and Yazaki, did not have a unified commander, and the nominal bannerman, Yasukatsu Kasawara, had already fled to Sagami with the Ashikaga Yoshiji after seeing that the battle situation was unfavorable. Mamiya Yoshiko and the others are completely fighting on their own. Especially after the death of Masanobu Oto, there was no one in Izu who could lead the Hojo family retainers who fought separately.

Although there were only 600 defenders in Kawazu Castle, what they did was indeed much more beautiful than the battle of Oto Masanobu in Nirayama Castle. Under the onslaught of the Takeda Army on the first day, they still held Kawazu Castle, which had only a double curved wheel.

Even if Takeda Shingen personally commanded outside the city, plus the two of them attacked from three sides, Kawazu Castle was still difficult to attack. The resistance of Jiushan City lasted only one day, so the city defense, garrison equipment, and number of defenders of Hejin City were inferior to Jiushan Castle. However, Mamiya Yokoku and Mamiya Nobutada nailed the main force of the Takeda Army to Kawazu Castle with a small city.

Due to the fact that Yamamoto Masanao and Yamamoto Ieji, who were among the Izu sailors, were omitted, this Izu navy did not support the two Mamiya Yoshiko and Mamiya Nobutada, who were still fighting. In addition, the Suwa Youmasuke of Fukone Castle only had more than 100 troops at hand, and he didn't dare to move without permission. The combined garrison of Shimoda Port and Shimoda Castle was only more than 2,000, and there was more than enough defense, so let's not talk about support. Yazaki Castle was surrounded by more than 1,900 troops of the two divisions of Murosumi Kotobu and Yokota Tsunamatsu, and the defender Nanjo Tsunashi only supported it for two hours before it was lost, and the defenders of more than 300 people defended themselves and killed all the troops below Nanjo Tsunatsuna.

Although the two uncles and nephews of Mamiya Yoshiko and Mamiya Nobutaka pinned more than 20,000 Takeda troops to Kawazu Castle on the first day and could not move, they seemed to have forgotten that there was also a Fujita Yasupang in the Takeda army. Seeing that the main force of the Takeda Army was helpless against a small city like Kawazu Castle, Fujita Yasumi made a timely suggestion - to set fire to the city.

This suggestion by Yasuma Fujita is not a whim. The fortification of Hejin Castle itself is made of wood, and its gates, arrowheads, and screens are all made of wood. In addition, the besieging side can set fire to the city as long as it waits for the right wind direction. The burning of the castle did not set the entire castle on fire, the Takeda army only needed to set the Ninomaru of Kawazu Castle on fire and then use the burning smoke to smoke the defenders in the castle.

In the early morning of the next day, while Mamiya Yoshiko and Mamiya Nobutada were still arranging defenses in Honmaru, the Takeda army relied on their numerical superiority to cover Bowashigaru and Iron Cannon Ashigaru on the one hand, and on the other hand, they ordered Zenashigaru to throw piles of tree branches and cloth looted from castle towns and nearby villages onto the edge of the board around Ninomaru. When Yoshiko Mamiya and Nobutada Mamiya got the news and left Honmaru to go to Ninomaru, the Takeda Army had already set the flammable materials on fire.

Soon, as the northwest wind blew, the fire instantly grew larger. Mamiya Yokoku and Mamiya Nobutada could only order all of Ninomaru's defenders to retreat to Honmaru. They couldn't put out the fire with the small amount of water they already had, and they wanted to hold on to Kawazu Castle for a few days until reinforcements from the Hojo clan arrived.

Of course, the guard general Mamiya Yokoku is not without colleagues to come to the rescue. The defenders of Shimoda Port, Iba Daisuke, led five hundred Ashigaru Kitakami generals to rescue the two uncles and nephews of Mamiya Yoshiko. However, in the early morning of the 7th, the reinforcements of Inobo University were ambushed by more than 900 men of the Takeda Army's Kudo Masasuke (Mamoru Nagato, son of Kudo Toratoyo, and his younger brother Naito Masato). Seeing that he could not enter the castle to support the Mamiya Koko, Ibo University led the remnants to retreat to Fukagen Castle. This support army of the Hojo Army retreated after losing more than 100 men, and Yasunobu Ita in Shimoda Castle did not know how to fight this battle, otherwise he would not have watched the gate of Shimoda Castle go missing.

As the fire gradually spread, almost all the screens around Ninomaru were ignited. Not only that, but several arrow turrets near Banping also burned. Before the battle, the two uncles and nephews of Mamiya Yoshiko patronized and gathered people to defend the city, and forgot to paint mud on the board screen and arrow turret. The fate of the two of them is also self-inflicted, and no one else can be blamed.

After a few hours, the fire burned down all the facilities such as the screens, arrows, and longhouses in Ninomaru, and there were very few defenders left in the Honomaru that had combat effectiveness.

Knowing that they could no longer hold Kawazu Castle, Mamiya Yoshiko and Nobutada Mamiya sent a samurai to the Takeda Army, hoping to exchange the lives of the remaining 200 defenders at the cost of their own seppuku.

Takeda Shingen did not object to this request, since he could open the city and reduce his own casualties, why not do it? Subsequently, in the afternoon, after more than 200 defenders put down their weapons and surrendered in the dark, Mamiya Yoshiko and Mamiya Nobutada also committed suicide in Honmaru. Hejin Castle, which had held out for a day and a half, was declared lost.

When Takeda Shingen was about to enter Fukone Castle, his ninjas came to report: Fukane Castle Keeper Suwa Right Masuke killed Iba University Sukeke, and will lead more than 400 city soldiers (plus the unmoraled Ibo University assistant Ashigaru) to surrender to the Takeda family.

Since the fall of Nirayama Castle, the Hojo family defenders in the entire Izu have been shaken a lot. The defenders of Kawazu Castle, Mamiya Yoshiko, and Mamiya Nobutada's uncle and nephew, were completely deeply favored by the Hojo family and had the courage to fight against the Takeda Army. Suwa Youmasuke is different, he is not a member of the Izu people, and he is afraid of the Takeda army, which can fight well. It is already rare that Suwa Youmasuke can hold out until the Takeda army attacks most of Izu Province before surrendering.

Kawazu and Fukin were lost one after another, and there was no longer a barrier in Shimoda Castle. Yasuei Shimizu was prescient, and he moved all the families and heirs of the owners of the ships of the Izu Navy to the Oshima Island of the Izu Islands, and placed them in the two yogashi of Okada and Oshima and the Mihara Mountains.

Yasuei Shimizu and the others of Izu are fine, but Yasunobu Ida, who is still in Shimoda Castle, is unlucky. Yasunobu Ita did not transfer Igami's 500 troops to Shimoda Castle, and he still had the idea that Shimizu Yasuei would support Shimoda Castle. Ryo Igami also agrees with Yasunobu Ita that Yasuei's main territory is in the area of Shimoda Castle and Shimoda Port, while the stone height of the Izu Islands is very low, so it is only suitable as a place to flee and take refuge.

At first, Kansuke Yamamoto was not sure whether Yasuei Shimizu would support the Hojo Army during the Takeda Army's siege, but just after the Takeda Army entered Fukane Castle to rest for a day, Yamamoto's righteous envoy came to the Takeda Army's camp. Yamamoto's righteous envoy came not to report on other matters, but to tell Yamamoto Kansuke about Yasuei's actions and the thoughts of the shipowners. After thinking about it for a while, Kansuke Yamamoto suggested that Takeda Shingen capture Shimoda Castle in two steps, first capturing Shimoda Port, and then Shimoda Castle.

The purpose of this proposal is to take Shimoda Port first to see if Yasuei Shimizu has any thoughts of supporting Yasunobu Ita. If Yasuei Shimizu does not come into battle, the Takeda Army will be able to quickly conquer Shimoda Castle and complete the occupation of all the land in Izu; If Yasuei Shimizu comes out to the rescue of Yasunobu Ita, then the leaders of the naval army who were transferred by the Takeda family, such as the Shosuke of the Aisu Warbu, will attack the Izu Islands or the back of the Yasuei Shimizu when the Takeda Army is engaged in the battle between Yasuei Shimizu.

And Yamamoto Kansuke and others didn't know that it was Yasuei Shimizu who was doing everything for Takeda Jun to see. Shimizu Yasuei has long placed more than 100 wind demons such as Wind Demon Kotaro on the big island, and Wind Demon Kotaro himself has lowered his value to help Shimizu Yasuei investigate every move of the Takeda Army, including the people who have planned to defect to the Takeda family in the Izu Water Army. The actions of Masanao Yamamoto and Yamamoto Ieji were too obvious, and Yasuhide Shimizu had prepared early. However, there is a deeper hidden inner circle among the Izu sailors that has not been discovered.

On the morning of March 9, Kawawa Noshimi led more than 800 troops to capture the port of Shimoda, and captured the defender Ibo Xiuliang. Of the 500 defenders, almost all of them were taken prisoner, except for the more than 50 people who died in battle. Takeda Shingen led more than 19,000 troops such as Takeda Shinshiro to besiege Shimoda Castle.

Just after Kawawa Nobumi captured Shimoda Port, before he could catch his breath, Yasuei Shimizu's sailors arrived. Shimizu Yasuei brought more than 2,000 sailors and ashigaru to come, and Kawawa Nominee commanded a hundred troops and retreated with more than 600 troops. However, Yasuei Shimizu will not let Hawa Shinshi leave here safely. After a fierce battle, Nobumi Kawawa escaped and fled to Shimoda Castle.

Yasuei Shimizu's arrival made Shingen Takeda feel that Izu was not very easy to take it all. Yamamoto Masanori, Yamamoto Ieji, Aisu Shosuke and others, who had previously agreed, were all confused by Yasuei Shimizu's 'holding on to his troops', which led to the Takeda Army to capture Shimoda Castle and Shimoda Port with their own strength.