The Battle of Regina Trench occurred in 1918 during the German Spring Offensive on the Western Front of World War I.
Eight Stosstruppen battalions of the Imperial German Army - Sturm-Battalion Nr. 4, Sturm-Battalion Nr. 14 (and its reserve battalion), Sturm-Battalion Nr. 2, Sturm-Battalion Nr. 8, Sturm-Battalion Nr. 17, Sturm-Battalion Nr. 15, and Sturm-Batallion Nr. 5 - were assembled for an offensive against the Canadian troops holding Regina Trench at the Ypres salient in Flanders as part of a general German push. Regina Trench was held by the 73rd, 51st, 15th, 22nd, 52nd, 145th, and 195th Battalions of the Canadian Expeditionary Force and the 2nd Battalion Rifle Brigade; the Canadians were battle-hardened and well-supplied with artillery and chemical weapons support.
The German stormtroopers charged across no man's land and initially suffered considerable losses while under Canadian rifle fire, as they had little to no cover apart from water-filled blast craters. However, the Germans were eventually able to overcome Regina Trench. The trench changed hands five times as the Canadians counterattacked, recaptured it, and forced the Germans to deploy reserves to hold the line. The Germans withstood several rounds of Green Cross (phosgene gas) during their defense of the captured Regina Trench, and, after holding back spirited Canadian counterattacks, they were able to press their attack and advance on the next Canadian trench, Victoria Trench. The Germans easily overwhelmed the trench, taking it within seconds of reaching the trenchline. Here, they were able to hold off several Canadian counterattacks before both sides drew off to recover from the battle. The Canadians suffered over 900 losses, while German losses numbered just under 700.