The War Guilt Clause is another name for Article 231 of the Treaty of Versailles, the beginning of the reparations section that stated Germany was to assume all responsibility for the damage caused during World War II. The Treaty of Versailles marked the end of the war, with countries on both sides of the war, the Allied and Axis powers, signing where appropriate.
Article 231 is known as the War Guilt Clause because it places full blame on the Germans. Many German citizens have felt this explicit statement added unnecessary humiliation. It was included as a way to reduce the reparations Germany would have to pay towards Belgium and France for the extensive damage caused.