Short answers, pulled from the story.
The Suez Crisis was triggered by Egyptian President Gamal Abdel Nasser's nationalisation of the Suez Canal on the 26th of July 1956, announced in a speech in Alexandria. The nationalisation followed Eisenhower's withdrawal of American financial support for the Aswan High Dam project on the 19th of July, itself a response to Nasser's recognition of the People's Republic of China and his arms deal with the Soviet Union via Czechoslovakia in 1955.
Israel, the United Kingdom, and France invaded Egypt in 1956. Israel attacked on the 29th of October, and Britain and France joined on the 31st of October after issuing a joint ultimatum. The three countries had secretly coordinated the operation through the Protocol of Sevres, agreed between the 22nd and the 24th of October 1956.
Britain and France withdrew primarily because of US financial pressure. The Bank of England lost $45 million between the 30th of October and the 2nd of November, the United States blocked British access to IMF assistance, and Eisenhower threatened to sell US sterling bond holdings, which would have devalued the pound and left Britain unable to import food and energy. A Soviet threat of rocket attacks on the three invading nations added further pressure.
Lester B. Pearson was Canada's Secretary of External Affairs. He designed the proposal for the first United Nations Emergency Force (UNEF), working alongside UN Secretary-General Dag Hammarskjold, which provided a face-saving mechanism for the ceasefire. For these efforts, Pearson received the Nobel Peace Prize.
The Suez Crisis confirmed that Britain and France could no longer pursue independent foreign policy without US consent, which historians argue signalled the end of Britain's role as a superpower. It strengthened Soviet influence in the Middle East and Arab world, accelerated France's decision to build its own nuclear deterrent, and laid groundwork for the Six-Day War in 1967 by leaving Egypt-Israel tensions unresolved. The canal reopened to shipping by the 24th of April 1957.
The Protocol of Sevres was a secret agreement reached between France, Israel, and the United Kingdom during meetings held between the 22nd and the 24th of October 1956 in Sevres, France. Under its terms, Israel would attack Egypt on the 29th of October; Britain and France would then issue a joint ultimatum demanding withdrawal, knowing Egypt would reject it; and Anglo-French military operations would begin on the 31st of October.