Following the 1920 Nebi Musa riots, the Yishuv's leadership created the Haganah, a nationwide defense organization. During the 1936–1939 Arab revolt in Palestine, the Haganah actively assisted the British Army, which in turn financed a Haganah-controlled Jewish police force known as Notrim. The crushing of the revolt decisively tipped the balance of power in Palestine in favor of the Yishuv. However, Britain also recognized a need to avoid antagonizing the wider Arab world. In 1937, the Peel Commission presented a plan for a Jewish state and an Arab state. After this was rejected, the British District Commissioner for the Galilee, Lewis Yellard Andrews was assassinated by Arab gunmen in Nazareth. In 1939, Britain announced the White Paper of 1939, which greatly restricted Jewish immigration and land purchases and called for a single unitary state in Palestine. In response to the White Paper, Jewish paramilitary group Irgun (an offshoot from the Haganah) began to carry out operations against the British.