Passage: The Battle of Verdun (French: Bataille de Verdun [bataj də vɛʁdœ̃]; German: Schlacht um Verdun [ʃlaxt ʔʊm ˈvɛɐ̯dœ̃]), was fought from 21 February to 18 December 1916 on the Western Front. The battle was the longest of the First World War and took place on the hills north of Verdun-sur-Meuse in north-eastern France. The German 5th Army began by attacking the defences of the Fortified Region of Verdun (RFV, Région Fortifiée de Verdun) and those of the French Second Army on the right (east) bank of the Meuse. Inspired by the experience of the Second Battle of Champagne in 1915, the Germans planned to capture the Meuse Heights, an excellent defensive position with good observation for artillery-fire on Verdun. The Germans hoped that the French would commit their strategic reserve to recapture the position and suffer catastrophic losses in a battle of annihilation, at little cost to the Germans, dug in on tactically advantageous positions on the heights.

Question: What war was the Battle of Verdun fought in?
First World War