The Battle of Ypres was a major battle of World War I that took place in the Belgian city of Ypres. It was fought between German and Allied forces from April 22nd to May 25th, 1915. The battle was part of a larger campaign known as the Second Battle of Ypres, which lasted from April 22nd to May 25th, 1915. During the battle, the Germans used chlorine gas for the first time in warfare, resulting in heavy casualties on both sides. The Allies were ultimately able to hold their ground, but at a great cost.