The Empire is a powerful military nation on a continent that looks much like early 20th century Europe. But in this world, magic is real. The Empire is involved in a war against the Entente Alliance, and fighting a poorly executed delaying action in the northern theater. Second Lieutenant Tanya Degurechaff leads a small platoon of mages. But there's something unusual about this lieutenant... she's only nine years old!

Tanya's new battalion is off the ground and running, and it's time for them to do their first mission: fight back a massive invasion by the Dakian Dukedom to the southeast. The enemy army numbers in the hundreds of thousands, but they've brought no air units at all, which makes them easy pickings for Tanya's highly trained force. After wiping out the enemy army, she heads straight for the enemy capital and launches an attack there.

After her easy victory over Dakia, it's time for a more difficult mission: aiding the destruction of the Entente Alliance to the north. The Alliance is being backed by the strong powers, and has equipment and training that in some cases rival the Empire. When Tanya arrives, the Alliance is striking a critical supply base with a bombing raid, and the local Empire force are too overwhlemed to defend against it. Can she get there to hold them off in time?

The war with the Entente Alliance is done, and it's back to the Rhine for Tanya and her forces. The Republic troops are highly trained, well-equipped, and stronger than any she's faced before. And in a distant hospital, a former Kingdom officer wakes up, with a mission from God imprinted on his mind...

Tanya's diminished smaller company attack the battalion of Allied Kingdom mages rather than retreat. Their company use their altitude advantage but suffer heavy losses, especially when Colonel Sioux uses an illegal Trench Gun.

Tanya just barely manages to restrain herself from disobeying her superior officers and attacking the Republic remanents. But the Republic forces have escaped overseas, and vowed to fight to the bitter end. The Empire has been victorious, but in its victory it has terrified the rest of the world and spurred them to action. Is true victory possible at all?