أحمد بن يحيى
The conservative rule of the imam was challenged by the rise of Arab nationalism. Yemen adhered to the United Arab Republic proclaimed by Egyptian president Nasser in 1958, joining with Egypt and Syria in a loose coalition called the United Arab States. However, the imam withdrew when Syria left the union in 1961. Pro-Egyptian militaries began to plot against the ruler. When Ahmad bin Yahya died in 1962, his son Muhammad al-Badr was quickly deposed as the plotters took over San'a. The Yemen Arab Republic was proclaimed. Muhammad al-Badr managed to escape to the loyalists in the highlands, and a civil war followed. Saudi Arabia supported the imam while Egypt dispatched troops to prop up the republicans. After Egypt's defeat against Israel in 1967, and the formation of a socialist people's republic in South Yemen in the same year, both intervening powers tried to find a solution in order to have their hands free. An agreement was finally reached in 1970 where the royalists agreed to accept the Yemen Arab Republic in return for influence in the government.