The rise of anti-Semitism in Europe, culminating in the Holocaust during World War II, had meant an increase of Jewish immigrants to a minority Jewish, majority Arab Mandate. During the 1936–39 Arab revolt and thereafter the British increasingly came to rely on Jewish police forces to help maintain order. Eventually, the resultant rise in ethnic tensions and violence between the Arabs and Jews due to Jewish immigration and collaboration would force the British to withdraw in 1947. (The area of their mandate east of the Jordan river had already become the independent state of Jordan in 1946.) The United Nations General Assembly developed a gerrymandered 1947 UN Partition Plan, to attempt to give both Arabs and Jews their own states from the remains of the British Mandate; however, this was rejected by the Arabs, and the situation quickly devolved into a full-fledged civil war.