The MC will be using his special ability, knowledge over defensive battles and deception to buy time in the war (or just to survive), while when he is not on the front line he will be pushing for the development of several weapons and strategy/mindset in order to have an edge against the germans.

Alternate world, with "Russia" as a tsardom still and "Germany" as an empire. World war 2 scenario. There is minor 'magic' that is publicized and with religion that might actually be real in this world, though the church has become secular and less extreme than their real life counterparts. How minor? You can hear so well that you turn into a radar against the enemy. You have the ability to become direct rockets in a certain direction through intense focus, called a Praying Hand, you are an anti-tank launcher. You have the ability to send messages from the battlefield to the capital, but only during mass and lighting candles on certain conditions. For most if not all 'magic' users, they are part of the church. The world geography is the exact same other than changes in names and cultures. Supposedly even the language is the exact same as their earth counterparts.

The power he has is that he can see further than others, in the form of an Real Time Strategy game view, the eagle view. Though only within a certain range. His troops who are loyal to him are included within his field of vision, and extends his fog of war.

While this power can be very useful in war, it is not overly used, and is not overpowered. War is still fought with flesh and blood.

The most important ability of our Protaganist however, should be his knowledge and nerdiness on war. A true nerd who have read the many leaked documents from World of Tanks and Warthunder.