The military phase of the Suez Crisis began on the 29th October 1956, when Israel invaded the Egyptian Sinai. Egyptian President Gamal Abdel Nasser had nationalized the Suez Canal on the 26th July, and months of tense negotiations failed to reassure Britain and France who secretly began preparing a military response – in alliance with Israel – to take back control of the canal.
Nasser had paid compensation to shareholders of the Suez Canal Company after he nationalized the waterway. However, both Britain and France were concerned about the potential economic problems that might ensue if Egypt chose to limit their access to the canal and thus to oil supplies from the Persian Gulf. Israel was already angry that Egypt had closed the canal to their shipping and blockaded the Gulf of Aqaba.
An agreement between the three allies was concluded at Sèvres in France on the 24th October. The Protocol of Sèvres called for a full-scale Israeli assault on Egyptian Sinai on the 29th October, which would be followed on the 30th with calls from Britain and France for the two sides to withdraw from the Canal Zone. They would then move in to the area and place it under Anglo-French control.
The Israeli invasion took place on the 29th October as agreed, but Nasser rejected the demands to withdraw his troops from the canal. In response British and French forces invaded the Egyptian city of Port Said on the night of the 5th-6th November, but were met with international condemnation that pressured British Prime Anthony Eden into calling ceasefire just a day later.