world. It went as the theocratic and largely medieval Imamate which became the first Arab state to accept Soviet aid. Beginning in 1955 Yemen entered into various treaties of friendship and from 1957 began receiving large amounts of Soviet arms as well as Soviet and Chinese military advisers. When the imam went abroad owing to illness, crown prince Muhammad al-Badr led a pro-Soviet party and communist activity increased. When the Imam returned in 1959, brutal repression ensued and communists were expelled. In April 1956 Yemen joined a defensive pact with Syria and Egypt, and in February 1958 it federated with the United Arab Republic. In parallel, clan violence erupted in Yemen and Aden, claiming hundreds of lives over 1956–60. The defensive pact move was conceived as a defensive measure against republican agitation, which urban nationalists still engaged in from British-occupied Aden. So long as Yemen was federated with the UAR, republicans would be deprived any assistance from Egyptian President Nasser. Although the federation lasted only for three years, crown prince al-Badr continued to portray himself as an Arab patriot, often railing against "reactionary Arab monarchs." Two states Arab nationalism influenced some circles that opposed the lack of modernization efforts in the Mutawakkilite monarchy. This became apparent when Imam Ahmad bin Yahya died in 1962. He was succeeded by his son, but army officers attempted to seize power, sparking the North Yemen Civil War. The Hamidaddin royalists were supported by Saudi Arabia, Britain, and Jordan (mostly with weapons and financial aid, but also with small military forces), whilst the republicans were backed by Egypt. Egypt provided the republicans with weapons and financial assistance but also sent a large military force to participate in the fighting. Israel covertly supplied weapons to the royalists in order to keep the Egyptian military busy in Yemen and make Nasser less likely to initiate a conflict in Sinai. After six years of civil war, the republicans were victorious (February 1968) and formed the Yemen Arab Republic. The revolution in the north coincided with the Aden Emergency, which hastened the end of British rule in the south. On 30 November 1967, the state of South Yemen was formed, comprising Aden and the former Protectorate of South Arabia. This socialist state was later officially known as the People's Democratic Republic of Yemen and a programme of nationalisation was begun. Relations between the two Yemeni states fluctuated between peaceful