The Battle of Bolimów was an inconclusive battle of World War I fought on January 31, 1915 between Germany and Russia and considered a preliminary to the Second Battle of the Masurian Lakes.
The German Ninth Army led by August von Mackensen attacked the Russian Second Army, under General Smirnov, near the Polish village of Bolimów, lying on the railway line connecting Łódź and Warsaw.
The Battle of Bolimów was the first attempt by the Germans at a large-scale use of poison gas; the eighteen thousand gas shells they fired proved unsuccessful when the xylyl bromide—a type of tear gas—was blown back at their own lines. The gas caused few, if any, casualties, however, since the cold weather caused it to freeze, rendering it ineffective.
The failure of the xylyl bromide caused the German commanders to call off their attack.
In response, the Russians sent 11 divisions, led by Vasily Gurko to launch a counterattack; German artillery repelled the Russian troops, who suffered 40,000 casualties.