On 21 February 1916 the Battle of Verdun started. It was one of the longest and bloodiest battles of the First World War in which about 300.000 soldiers lost their lives. The Germans were commanded by Erich von Falkenhayn. His plan was to draw as much French soldiers to the Verdun sector as possible in order to kill as many as the Germans could. He knew the French, under Joseph Joffre, would do as much as possible to defend Verdun, it turned out to be very important to them in the Franco-Prussian War (1870-1871) and Von Falkenhayn correctly assumed the French would defend it with their last drop of blood. However, the Germans eventually lost the battle, which lasted for nine months, three weeks and six days and in which both armies fielded over one million soldiers.
Below a great documentary about this battle (which can also be found in the Video menu).
Stand Your Ground, Military History 1789-1919. 