The United Arab Republic (UAR; Arabic: الجمهورية العربية المتحدة‎ ‎ "al-Jumhūrīyah al-'Arabīyah al-Muttaḥidah ") was a state, and between 1958 and 1961, a short-lived political union between Egypt and Syria.
 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.
Nur al-Din Kahala (Arabic: نور الدين كحالة‎ ‎ ) (1908—1965) was a Syrian politician during the United Arab Republic (UAR) period (1958-1961).
Gamal Abdel Nasser Hussein (Arabic: جمال عبد الناصر حسين‎ ‎ , ] ; 15 January 1918 – 28 September 1970) was the second President of Egypt, serving from 1956 until his death.
 Nasser led the 1952 overthrow of the monarchy and introduced far-reaching land reforms the following year.
 Following a 1954 attempt on his life by a Muslim Brotherhood member, he cracked down on the organization, put President Muhammad Naguib under house arrest, and assumed executive office, officially becoming president in June 1956.
Akram Al-Hourani (Arabic: أكرم الحوراني‎ ‎ , also transcribed El-Hourani, Howrani or Hurani) (1912 – February 24, 1996), was a Syrian politician who played a prominent role in the formation of a widespread populist, nationalist movement in Syria and in the rise of the Ba'ath Party.
 He was highly influential in Syrian politics from the beginning of the 1940s until his departure into exile in 1963.
 Al-Hourani held various positions including a government ministry and the joint vice-presidency of the United Arab Republic.
The history of Egypt under Gamal Abdel Nasser covers the period of Egyptian history from the Egyptian Revolution of 1952, of which Gamal Abdel Nasser was one of the two principal leaders, spanning Nasser's presidency of Egypt from 1956, to his death in 1970.
 Nasser's tenure as Egypt's leader heralded a new period of modernization, and socialist reform in Egypt, and a staunch advocacy of pan-Arab nationalism (including a short-lived union with Syria), and Developing World solidarity.
 His prestige in Egypt and throughout the Arab World soared in the wake of his nationalisation of the Suez Canal in 1956, and Egypt's political victory in the subsequent Tripartite Aggression, but was damaged badly by Israel's successful invasion and occupation of Egyptian and Arab territory in the Six-Day War of 1967.
The origins of the Six-Day War, which was fought between June 5 and June 10, 1967 by Israel and the neighboring states of Egypt (known then as the United Arab Republic, UAR), Jordan, and Syria, include both longstanding and immediate issues.
 At the time of the Six-Day War, the earlier foundation of Israel, the resulting Palestinian refugee issue, and Israel's participation in the invasion of Egypt during the Suez crisis of 1956 continued to be significant grievances for the Arab world.
 Arab nationalists, led by Egyptian President Gamal Abdel Nasser, continued to be hostile to Israel's existence and made grave threats against its Jewish population.
 By the mid-1960s, relations between Israel and its Arab neighbors had deteriorated to the extent that a number of border clashes had taken place.
Egypt–Palestine relations are the bilateral relations between the Arab Republic of Egypt and the Palestinian National Authority.
 Egyptian President Gamal Abdel Nasser was a strong supporter of the Palestinian cause and he favored self-determination for the Palestinians.
 Even today Egypt maintains strong relations with the Palestinian Authority and it favors peace between both Israel and Palestine.
Mansur al-Atrash (Arabic: منصور الأطرش‎ ‎ ; 3 February 1925 – 14 November 2006) was a Syrian politician and journalist.
 Together with fellow university students, Atrash became a founding member of the Ba'ath Party and its Syrian regional branch in 1947.
 During the presidency of Adib Shishakli (1951–54), he became an anti-government activist and was imprisoned twice, only to be released in an unsuccessful attempt by Shishakli to gain the support of Atrash's father, Sultan.
 In the year Shishakli was overthrown, Atrash was elected to parliament and turned down an offer to serve in Said al-Ghazzi's government.
 During the period of the United Arab Republic (1958–61), Atrash became a strong supporter of Egyptian president and pan-Arab leader Gamal Abdel Nasser.
 He opposed Syria's secession from the UAR and turned down offers to serve in successive separatist governments in protest.
Bouthaina Shaaban (Arabic: بثينة شعبان‎ ‎ ) (born 1953) is a Syrian politician and is currently the political and media adviser to the President of Syria.
 Shaaban served as the first Minister of Expatriates for the Syrian Arab Republic, between 2003 and 2008, and has been described as the Syrian government's face to the outside world.
The First Field Army was a branch of the Egyptian armed forces as the United Arab Republic and was based in Syria and called the name of President Gamal Abdel Nasser.
 During the period of the United Arab Republic, the army based in Syria was designated the First, and the other armies in Egypt the Second and Third.
 By 1973 any use of the 'First' designation in Syria had ended, but this did not stop erroneous Western press reporting that forces of the central military district around Cairo were designated the First Army.

Question: Mansur al-Atrash, was a Syrian politician and journalist, during the period of the United Arab Republic (1958–61), Atrash became a strong supporter of Egyptian president and which pan-Arab leader, who was the second President of Egypt, serving from 1956 until his death?
Answer: Gamal Abdel Nasser Hussein