What started the Arab-Israeli War of 1956?

Answer 1

The Arab-Israeli War of 1956 (Commonly called the Suez Crisis) began when British and French forces, which were jointly controlling the Suez Canal were forced out by Gamal Abdel Nasser during his attempt to nationalize the Canal. The British and French were not interested in losing the canal to the Egyptians and neither were the Israelis. The British and French motivation was to avoid having to pay tolls and worry about crossing easily. The Israeli motivation was to be allowed to continue crossing between the Mediterranean and Red Seas as Egypt did not recognize Israel at the time.

Britain and France incentivized Israel (and joined with Israel) to attack Egypt and take the Suez Canal back. Israel successfully conquered all of the Sinai Peninsula and even landed a foothold on the west bank of the Suez Canal (which meant that they effectively controlled it). The United States, however, intervened and requested that Israel withdraw to the 1949 boundaries under the condition that Egypt return the Canal to British and French joint control.
Gamal Abdel Nasser nationalized the Suez Canal, which angered the British and the French.

Answer 2

29 October - 7 November 1956
It began on October 29, 1956 once Britain, France, and Israel attacked Egypt.
...President Nasser of Egypt decided to nationalize the Suez Canal, taking control away from the Suez Canal Company (dominated by the French and English) that had until then run and controlled the Suez Canal.

Answer 3

Egypt blocked Israel's direct access to the Red Sea, effectively preventing Israel from having commerce with Iran, its primary petroleum supplier at the time.