The Russia that is now fighting the Great War is not the Russia of even just ten years before. In 1905 the Russians were crushed by the Japanese in the Russo-Japanese War, having their fleet sunk by Homing Fireshells and the armies whooped by Unicorn Cavalry and Rapid-Firing Magiguns. The defeat allowed a traveling mystic named Rasputin to come to Czar Nicholas II, and offered to help him rebuild Russia (as well as save his son, the heir to the throne, possessed by Demons).
It was ambitious and borderline insanity, but the Czar was willing to do anything to make sure Russia would never be defeated again. So he allowed Rasputin to do whatever he needed to.
Rasputin turned out to be more than a mystic: he was perhaps the most powerful necromancer that lived. His first order of business was the resurrect the greatest leaders of Russia: Peter and Catherine the Great, Ivan the Terrible, and General Mikhail Kutuzov, and fused their somehow still intact brains into one super brain, which he then transplanted into himself. This made him instantly perhaps the smartest and most brilliant strategist in history, at the cost of leaving him undead (and needing to eat 100 people a day, which were then also turned into Zombies). He also created a device to bring back the millions of Russians who had died in warfare into Zombies, making Russia now the strongest Zombie power in the world.
Nicolas II, now hiding in his palace with his family and refusing to leave in fear of being eaten by the Zombie hordes now infesting Russia, allowed Russia to enter the Great War, and the Zombie Hordes were unleashed on the Germans and Austria-Hungarians. Although Russia made huge strides, the undead were no match for the technologically (and magically) superior armies of the Germans, and the just stupidly lucky Hapsburgs.
But then the Alien Space Bats came to Earth. Rasputin turned his Zombies away from Germany and Austria, and sent them to the ASB's. And, to the surprise of the world, Russia quickly wiped out the entire Alien fleet, even though they had been stalemated by the Central Powers before.
The victory was short lived, however. Now the Alien Space Bats had all been turned into Zombies, and Rasputin was now the center of a giant hivemind of millions upon millions of undead Russians and Aliens. And he was hungry for more live beings!
Where does Zombie Rasputin and his hordes attack now?