The Haganah was the underground military organization of the yishuv in Erez Israel from 1920 to 1948. After the British conquest of Erez Israel, it was thought that there would not be a need for a Jewish defense organization. However, The Arab riots in 1920 and 1921 made clear that the Britishcould not be relied on, and that the Jews had to create their own independent defense force. In June 1920, the Haganah was founded. It was during the Arab revolt of 1936-39 in which it became into a military body. The Haganah protected Jewish settlements and after the infamous British White Paper of 1939 supported illegal immigration and organized demonstrations against British anti-immigration policy. During World War II the Haganah provided volunteers for British units, cooperated with British intelligence, and conducted commando missions, including that of Hannah Szenesh and others in Hungary. After the independence of the State of Israel the Haganah became the basis and core of the Israeli army.