army also brutally suppressed the Tikveš uprising and terrorized the Bulgarian population in the rebelling regions. According to some sources 363 civilian Bulgarians were killed in Kavadarci, 230 - in Negotino and 40 - in Vatasha. 1914–1918: World War I World War I was the first major international conflict to take place following the codification of war crimes at the Hague Convention of 1907, including derived war crimes, such as the use of poisons as weapons, as well as crimes against humanity, and derivative crimes against humanity, such as torture, and genocide. Before, the Second Boer War took place after the Hague Convention of 1899. The Second Boer War (1899 until 1902) is known for the first concentration camps (1900 until 1902) for civilians in the 20th century. 1915–1920: First and Second Caco War During the First (1915) and Second (1918–1920) Caco Wars waged during the United States occupation of Haiti (1915–1934), human rights abuses were committed against the native Haitian population. Overall, American troops and the Haitian gendarmerie killed several thousands of Haitian civilians during the rebellions between 1915 and 1920, though the exact death toll is unknown. Mass killings of civilians were allegedly committed by United States Marines and their subordinates in the Haitian gendarmerie. According to Haitian historian Roger Gaillard, such killings involved rape, lynchings, summary executions, burning villages and deaths by burning. Internal documents of the United States Army justified the killing of women and children, describing them as "auxiliaries" of rebels. A private memorandum of the Secretary of the Navy criticized "indiscriminate killings against natives". American officers who were responsible for acts of violence were given Creole names such as "Linx" for Commandant Freeman Lang and "Ouiliyanm" for Lieutenant Lee Williams. According to American journalist H. J. Seligman, Marines would practice "bumping off Gooks", describing the shooting of civilians in a manner which was similar to killing for sport. During the Second Caco War of 1918–1919, many Caco prisoners were summarily executed by Marines and the gendarmerie on orders from their superiors. On June 4, 1916, Marines executed caco General Mizrael Codio and ten others after they were captured in Fonds-Verrettes. In Hinche in January 1919, Captain Ernest Lavoie of the gendarmerie, a former United States Marine, allegedly ordered the killing of nineteen caco rebels according to American officers, though no charges were ever filed against him due to the fact that no physical evidence