The union began in 1958 and existed until 1961, when Syria seceded from the union after the 1961 Syrian coup d'état. In 1971 the UAR was renamed the Arab Republic of Egypt. The president was Gamal Abdel Nasser. The UAR was a member of the United Arab States, a loose confederation with North Yemen, which was dissolved in 1961.
Established on 1 February 1958, as a first step towards a larger pan-Arab state, the UAR was created when a group of political and military leaders in Syria proposed a merger of the two states to Egyptian President Gamal Abdel Nasser.
Pan-Arab sentiment traditionally was very strong in Syria, and Nasser was a popular hero-figure throughout the Arab world following the Suez War of 1956. There was thus considerable popular support in Syria for union with Nasser's Egypt. The Arab Socialist Ba'ath Party was the leading advocate of such a union.
In mid-1957 western powers began to worry that Syria was close to a Communist takeover; it had a highly organized Communist Party and the newly appointed army's chief of staff, Afif al-Bizri, was a Communist sympathizer. This caused the Syrian Crisis of 1957 after which Syrians intensified their efforts to unite with Egypt. Nasser told a Syrian delegation, including President Shukri al-Quwatli and Prime Minister Khaled al-Azem, that they needed to rid their government of Communists, but the delegation countered and warned him that only total union with Egypt would end the "Communist threat". According to Abdel Latif Boghdadi, Nasser initially resisted a total union with Syria, favoring instead a federal union. However, Nasser was "more afraid of a Communist takeover" and agreed on a total merger. The increasing strength of the Syrian Communist Party, under the leadership of Khalid Bakdash, worried the Syrian Ba'ath Party, which was suffering from an internal crisis from which prominent members were anxious to find an escape. Syria had had a democratic government since the overthrow of Adib al-Shishakli's military regime in 1954, and popular pressure for Arab unity was reflected in the composition of parliament.
When on 11 January 1958 al-Bizri led a Syrian delegation composed of military officers to Cairo, and personally encouraged Syrian-Egyptian unity, Nasser opted for a quick merger. Only Syrian advocates of unity, including Salah al-Din Bitar and Akram El-Hourani had prior knowledge of this delegation; Quwatli and Azem were notified a day later and considered it tantamount to a "military coup".