The Iraqi revolt against the British, also known as the 1920 Iraqi Revolt or Great Iraqi Revolution, started in Baghdad in the summer of 1920 with mass demonstrations by Iraqis, including protests by embittered officers from the old Ottoman army, against the British occupation of Iraq. The revolt gained momentum when it spread to the largely tribal Shia regions of the middle and lower Euphrates. Sheikh Mehdi Al-Khalissi was a prominent Shia leader of the revolt. Sunni and Shia religious communities cooperated during the revolution as well as tribal communities, the urban masses, and many Iraqi officers in Syria. The objectives of the revolution were independence from British rule and creation of an Arab government. Though the revolt achieved some initial success, by the end of October 1920, the British had crushed the revolt. Although the revolt was largely over by the end of 1920, elements of it dragged on until 1922. During the 1920 revolt, another anti-British rebellion took place in the north Iraq by the Kurds, who were trying to gain independence. One of the major Kurdish leaders of the Kurdish revolt was Sheikh Mahmoud Barzanji.
Answer this question: How many years did the revolt span?
2