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.