25 May 1915
End of the second battle of Ypres. The Germans have wasted their best chance of achieving a breakthrough with poison gas by attacking without proper reserves. This gives the Allies time to prepare gas masks and the chance of a breakthrough is gone.
War at Sea
HMS Vengeance avoids an attack by U-21 off Gallipoli. The German submarine goes on to sink HMS Triumph
How to cite this article: Rickard, J (28 December 2007), 25 May 1915, https://www.historyofwar.org/firstworldwar/daybyday/1915_05_25.html