What was the 'Suez Crisis' in 1956 and why was it so significant?

The Suez Crisis was an international incident that occurred in 1956, and involved the possession of the Suez canal located in Egypt. The United Kingdom had effectively owned the canal since the mid-1870s, when then-Prime Minister Benjamin Disraeli purchased its use for £4 million. It became a vitally important gateway for the British Empire through its hold over many parts of colonised Africa and the Middle East. 

In 1956, Egyptian President Gamal Abdal Nasser nationalised the canal and brought it under Egyptian control. 

French Prime Minister Guy Mollet, Israeli President David Ben-Gurion and British Prime Minister Anthony Eden then concocted a plan whereby the Israeli army would launch an initial ground invasion of Egypt, which would provide the necessary pretext for an Anglo-French invasion shortly after. Their interests overlapped with one common goal: to remove Nasser from power and dminish the influence of Egypt. The British wanted to retake the canal and maintain the power of the empire, whilst the French wanted the removal of Nasser due to Egypt's support of the FLN rebels in Algeria. Israeli-Egyptian relations had been deterioirating following the 1948 Arab-Israeli war, with flashpoints involving Egyptian raids across the Israeli border, and subsequent Israeli military responses. 

The Israeli invasion occurred on 29 October, and the resulting Anglo-French invasion was carried out on the 5 November. After neutralising the Egyptian Air Force, the alliance had almost taken the entire canal by the 6 November, when the United Nations General Secretary Dag Hammarskjöld called for a ceasefire, resulting in a suspension of the military progress.  

Globallly, the trialateral alliance was completely isolated both from international governments, such as the United States, and from domestic popular opinion. US President Dwight Eisenhower, fearing Soviet intervention and the triggering of an armed conflict with the Soviet empire, furiously demanded that the alliance withdraw from the canal. UK Prime Minister Eden, having been elected in 1955 with sky-high expectations, was forced to resign with the canal lost, Britain's global standing shattered and his personal reputation in tatters. 

Its significance rests on the juxtaposition between the initial military success and the political humiliation and isolation. In military terms, the alliance was a tremendous success and made very short work of overwhelming the Egyptian military and nearly retaking the canal before the ceasefire was put in place.

However, it represented a very rare instance where the Soviet Union and the US had mutual interests in threatening a third party to desist, and ultimately symbolised the decline of the British superpower in place of the bipolar Cold War between the US and the Soviet Union. Many historians portray Soviet leader Nikita Khruschev's 1956 invasion of Hungary as demonstrative of this development; with the UK and France still reeling from the Suez crisis he could feel more emboldened to take unilateral military action in Europe, with little resistance. Ultimately, as France was in the midst of a brutal war in Algeria which would soon end in 1962, it signified the process where the colonial European powers declined whilst the two superpowers ascended.