On February 8, 1963, an army coup was staged, overthrowing the Iraqi Nationalist government of Abd al-Karim Qasim in favour of the pan-Arabist Abdul Salam Arif. The two had both been members of the free officers movement that orchestrated the overthrow the western-aligned Hashemite monarchy in the 14 July Revolution, but Ideological differences between the two caused tension. The coup had been planned for over a year, and followed one and a half months of Ba'athist agitations and protests against Qasim. After the coup the new regime instituted Arif as president and moved swiftly to eliminate its opponents, primarily the Iraqi Communist Party followers of Qasim. Thousands of leaders and key cadres of the Communist Party were detained, tortured and often killed, leaving the party in organizational disarray.