In August 1914, as part of the Schlieffen Plan, the German Army invaded and occupied the neutral nation of Belgium without explicit warning, which violated a treaty of 1839 that the German chancellor dismissed as a "scrap of paper" and the 1907 Hague Convention on Opening of Hostilities. Within the first two months of the war, the German occupiers terrorized the Belgians, killing thousands of civilians and looting and burning scores of towns, including Leuven, which housed the country's preeminent university, mainly in retaliation for Belgian guerrilla warfare, (see "francs-tireurs"). This action was in violation of the 1907 Hague Convention on Land Warfare provisions that prohibited collective punishment of civilians and looting and destruction of civilian property in occupied territories.