The United States occupied Haiti -- to restore order and protect American interests and property -- in the wake of the assassination of Haiti's president Vilbrun Guillaume Sam on 28 July 1915 and maintained a force of Marines to occupy the island until 1934. While U.S. forces were able to pacify the cities quite quickly, the Cacos maintained a rebellion in the mountainous areas to the north. Despite lack of local support, near Cap-Haïtien, the Cacos threatened to defeat the U.S. Marines at the Battle of Fort Dipitie, but skillful use of reinforcements enabled the Marines to launch a surprise counter attack that resulted in the entire Cacos force being either killed or taken prisoner. The marines then slowly advanced upon the mountainous Cacos territory, eventually trapping and defeating the remnants of the guerilla force at the Battle of Fort Rivière.