The Attack of the Dead Men, or the Battle of Osowiec Fortress, was a battle of World War I that took place at Osowiec Fortress (now northeastern Poland), on August 6, 1915.

The incident received its grim name from the bloodied, corpse-like appearance of the Russian combatants after they were bombarded with a mixture of poison gases, chlorine and bromine by the Germans. While coughing up blood and often pieces of their inner organs, the Russians covered their faces with cloths and managed to rout the German troops.