The battle of Verdun was one of the longest, bloodiest, and most-ferocious battles of the war; French casualties amounted to about 400,000, and German about 350,000. 
Erich von Falkenhayn believed that the war would be won or lost in France, and he felt that a strategy of attrition was Germany’s best hope of achieving its goals. In a letter to German Emperor William II in late 1915, he argued that Britain was the most formidable of the Allied powers, but he conceded that it could not be assaulted directly, save by submarine warfare, as the British sector of the Western Front did not lend itself to offensive operations (an assessment that would be proved correct at the First Battle of the Somme). In Falkenhayn’s view, Britain’s “real weapons” in the war were the French, Russian, and Italian armies. He regarded Russia as already paralyzed and Italy as unlikely to affect the outcome of the war, concluding, “Only France remains.” Falkenhayn stated that a breakthrough en masse was unnecessary and that instead, Germany should bleed France to death by choosing a point of attack “for the retention of which the French would be compelled to throw in every man they have.”
The fortress of Verdun along its surrounding fortifications along the Meuse River was selected because it threatened the main German communication lines, it represented a salient in the French defences, and the loss of such a storied citadel would be an enormous blow to French morale.