The major battlefields of the First World War lay along the Upper Rhine in the Vosges Mountains, Alsace, and Lorraine. However, fighting also took place in Belgium and on France's northeastern border, resulting in heavy losses on both sides. The hostilities of 1915-16 reached their climax in and around Verdun. The battle was the longest and bloodiest of the entire First World War. This documentary depicts the events in Europe in 1917, the year of decision. In addition to England, France, and Russia, the United States also declared war on Germany.