WWI gave rise to many horrifying battle tactics, including the use of poison gas. One of the most unsettling WWI fights was the battle at the Osowiec Fortress, where Germans fought what looked like real-life zombies. On August 6, 1915, the Germans released gas on Russian and Polish soldiers, effectively destroying their enemies' lungs and throats. Many soldiers expired from the devastating effects of the gas.
Yet somehow, a group of fighters managed to live through the initial strike and hold down the fortress. When the Germans reached the tower, they saw dozens of disfigured and bleeding combatants coming at them. "The Attack of the Dead Men," as it was known, spawned legends about Russian soldiers rising from the grave to fight.