By December 1941, the German situation in Romania had begun to deteriorate.

Although they managed to capture the plains of western Transylvania and capture many cities www.biquge.info they began to be frequently harassed by Romanian guerrillas as they advanced eastward into the Romanian mountains.

The guerrillas, dressed in civilian clothing and fluent in Romanian, looked not much different from ordinary Romanian residents, but their equipment and combat effectiveness were on the level of regular troops.

It is clear that these so-called "partisans"

Actually drawn from the regular Romanian army.

Before the German invasion, with the help of the Soviets, they established several bases in the mountains of Transylvania, storing large quantities of weapons, ammunition, food and other military supplies.

Most of the partisan units were equipped with radio communication equipment to facilitate communication with the regular army, and they could also report the enemy's position to the command and request air strikes.

Some partisans were even armed with 76 anti-tank guns of the caliber ZIS-3, capable of delivering effective blows to German tanks.

As for mortars, machine guns, submachine guns, and so on, they were all basic equipment for these guerrillas who had been converted from the regular army.

The attacks of the guerrillas greatly slowed down the German army's advance, and their logistical supply was greatly affected, and from time to time some convoys transporting supplies were attacked and looted by the guerrillas, which allowed the guerrillas to obtain a large amount of equipment and military supplies.

Nevertheless, the threat from the Ploiesti oil fields was not diminished in the slightest by the blocking of the Germans in the mountains of Transylvania.

In fact, in addition to Transylvania, the Germans deployed troops on the Bulgarian side, which, together with the Bulgarian army, marched north from the Bulgarian border to attack Romania.

Fortunately, the Soviet Red Army had already made corresponding deployments on the border between Romania and Bulgaria, and a large number of Soviet Red Army troops arrived at the front line in a short period of time and had an advantage in terms of troops.

Coupled with the fact that the terrain was flat and the Soviet Red Army, which had a large number of tanks, was in an advantageous position on the battlefield, the Bulgarian and German armies were not able to break through the defensive lines of the Soviet and Romanian armies, and the Bucharest and Ploiesti oil fields were safe for the time being.

At the same time as the fierce fighting at the front, the rear of the Soviet Union and Germany was also in full swing, and the research and development of new weapons was being carried out.

The appearance of Manturov certainly improved the weapons technology of the Soviet Union, and the appearance of weapons and equipment such as the La-7 fighter, the Yak-3 fighter, the Tu-2 bomber, and the T-34/85 appeared in advance, which greatly enhanced the combat strength of the Soviet Red Army.

However, it was precisely because of the early appearance of these weapons that the Germans had to concentrate more resources and energy on developing new weapons that could fight them.

It was in this environment that the No. 4 tank upgraded its main gun in advance, and installed the 75 mm caliber, 43 times the diameter of the KWK 40 tank gun, eliminating the original KWK 37 tank gun, which greatly improved the armor-piercing ability of the No. 4 tank.

In addition, in order to surpass the Soviet Union in terms of firepower and protection of the tank, Hitler also deployed more resources and more manpower to participate in the research and development of the Tiger tank, and finally the Tiger tank also appeared in advance and went to the battlefield in advance to fight.

Manturov had already expected this outcome, as he was not playing a game, and his opponents were living figures, not artificial intelligence (AI) with rigid minds and only playing by routines.

So far, Soviet tanks are among the world's leading in almost every aspect, except for the quality of production.

However, the Soviet aircraft were inferior to other world powers (the United States, Great Britain, Germany) (that is, the Yak-3 was still in a relatively leading position in terms of low-altitude performance, firepower and high-altitude performance...... It's inferior).

Therefore, the top priority of the Soviet military industry is to develop a fighter with greater firepower, and in addition, to find ways to improve the high-altitude combat capability of existing fighters to make up for the shortcomings of Soviet fighters in high-altitude performance.

So far, the only high-altitude fighters in the USSR were the MiG-3 and the Pe-3 (adapted from the Pe-2 bomber).

But both the MiG-3 and the PE-3 are still slightly inferior in their high-altitude performance compared to German fighters.

If a completely new high-altitude fighter is developed, even if the Soviet Union has the ability to develop aircraft and has enough manpower and material resources, it will be difficult to complete it in a short time.

In addition to developing a completely new fighter, the Soviet aviation industry could also improve the flight performance of the MiG-3 by replacing it with a better engine.

Now, the Soviet MiG-3 fighters are still using the AM-35 liquid-cooled V-12 piston engine from the Mikulin Design Bureau for the time being.

Its output is only 1350 hp and its top flight speed is only 640 km/h, which is slower than the Lar-7, Yak-3, and the German BF-109 and FW190.

If you switch to a more powerful engine, the flight speed of the MiG-3 will be increased considerably.

In fact, in the history we are familiar with, the Soviets experimented with the MiG-3, a high-altitude interceptor, with different engines, and its flight performance has also been greatly improved.

According to the results of the experiments of the Soviet aviation department, the MiG-39 (И-3) equipped with AM-231A engines was able to reach a maximum flight speed of 707 kilometers per hour, which was faster than the BF-109 and FW190, and the high-altitude performance was also greatly improved.

However, because the Mikulin series engines were in short supply and were preferentially assigned to the Il-2 production line (Stalin's preference), the I-231 (that is, the MiG-3 fighter) could not be put into large-scale production.

As a result, the MiG-3 fighters withdrew from the stage of history and were replaced by fighters of the Lavochkin series, the Yak series, as well as fighters aided by Britain and the United States (including the P-47, Spitfire).

However, developing a new engine is not an easy task, as the structure of the engine is more complex and sophisticated, and it takes much longer than designing a gun.

In addition, the Soviet Union was relatively backward in terms of engine technology (after all, the Soviet Union started late, and compared with Britain, the United States and Germany, the technology was naturally not so mature.)

Naturally, the progress of research and development is one step slower.

Fortunately, the Soviet Union's aircraft engine technology was not too backward, and after the development of three five-year plans, the technological distance between the Soviet Union and other countries in this regard has become closer and closer, and the performance of the aircraft has reached a level that can be on par with Britain, the United States, and Germany.