Suez Crisis shows what happens when friends don’t share

British prime minister, Anthony Eden, and US president, Dwight Eisenhower, after a conference at the White House in 1956. JR AP/Press Association Images

Sixty years ago, the Suez Crisis triggered one of the greatest conflicts between allies in NATO history. Britain, France and Israel invaded Egypt after Gamal Abdel Nasser, the Egyptian president, nationalised the Suez Canal. But far from supporting the invasion, the US president, Dwight Eisenhower, feared it would array the “third world” against the West to the benefit of the USSR.

The US condemned its allies’ military action, demanded their forces leave Egypt and used the considerable economic and diplomatic tools at its disposal to force compliance.

The term “Suez” became shorthand for discord among allies – and there were indeed many obstacles hindering cooperation. Most importantly, the perceived stakes were not the same on the American and European sides of the Atlantic. Compared to Britain and France, US holdings in the Suez Canal Company were insignificant – and America did not rely nearly as much on oil from the Middle East shipped through the waterway.

Paradoxically, however, the crisis was also exacerbated by excessive agreement between the allies – especially where Britain and the US were concerned. Leaders on both sides mistakenly believed their perceptions of the threat Nasser posed were roughly the same as their ally’s – and, interestingly, this mistake had been encouraged by their communications with one another.

Common misunderstanding

Historians have explained the allies’ misperception of one another’s positions during Suez by arguing that they were eager to cooperate, which in turn meant that they wished to avoid discussion of their potential differences. But this assumes that Eisenhower, Britain’s prime minister Anthony Eden and other senior leaders were aware of their disagreements about Nasser – and this is at odds with their private and public statements at the time.

Eisenhower wrote to Eden: “I do not, repeat not, differ from you in your estimate of [Nasser’s] intentions and purposes.” Eden told his cabinet that the firmness of Britain’s stance was winning over US sceptics – and Harold Macmillan agreed that Eisenhower was determined “to bring Nasser down”.

Leaders did agree that Nasser was a threat and that it was undesirable for Egypt to exercise unilateral control over the canal. These beliefs were common information and were thoroughly discussed during allied meetings and in leaders’ correspondence with one another from August 1956 onwards. But unique to both sides were their beliefs about the magnitude of the threat Nasser represented

Given the risk to their country’s economic welfare and influence in the Middle East, Eden and other British leaders saw Nasser as a “Hitler on the Nile”. Those in Washington, although not fond of Nasser, saw him as much less menacing – more of a “stumbling block”, as Eisenhower wrote in his diary. These divergent profiles of Nasser were not seriously debated at a high level until a month-and-a-half after the crisis began.

British tanks disembarking at Port Said, 1956. Royal Navy photographer, courtesy of Imperial War Museums, CC BY

Even then, US and UK leaders erred in thinking their disagreements were a relatively minor bump in the road. In October, Eden’s secretary Norman Brook confidently told the prime minister there had been “a substantial advance in Anglo-American agreement on objectives and methods … The American agencies have joined with us in declaring that our joint objectives require Nasser’s removal from power.” As a result of these mistaken assessments, the US was caught off guard by the invasion of Egypt – and Britain was equally unprepared for the US response.

The illusion of unanimity between the senior political leaders in Washington and London was able to persist despite the “special relationship”, which included sharing large amounts of secret intelligence about Egypt. Officials in the two countries were looking at similar information but drawing different conclusions from it.

Eisenhower ordered the newly created Board of Consultants on Foreign Intelligence Activities to conduct a review of US intelligence services’ assessments made during the crisis to try to figure out how he had been so mistaken about British intentions. The president’s insistence on an investigation again shows that he was genuinely surprised by the episode’s outcome.

Psychology of sharing information

A novel explanation of the allies’ mistaken perceptions of one another in 1956 concerns the psychology of communication and decision-making in coalitions. Even when individuals have diverse interests and knowledge, they often unwittingly avoid areas of difference, instead disproportionately sharing and discussing information that all the members of their decision-making group already know.

British and US strategists differed in their assessment of Nasser’s threat to Middle East security. Bibliotheca Alexandrina, CC BY

This happens for several reasons. Most simply, information that all group members know (called “common information”, such as the belief that Nasser shouldn’t exercise unilateral control over the canal) is more prevalent than information that is only held by one or a few members of the group (“unique information”, like the British belief that Nasser was akin to Hitler).

Common information is thus more likely to be brought up by chance alone, because there is more of it than unique information. This also means common information is likely to be discussed first, which has the effect of establishing it as the “baseline” against which new evidence is judged and interpreted. Decision-makers’ beliefs are slow to move away from the initially discussed common information. In the case of Suez, because US and British leaders discussed their agreement that Nasser posed a threat early on, they inferred that their judgements about the size of that threat were roughly similar.

Lastly, people are predisposed to try to confirm beliefs they already hold. When a party to a discussion brings up information the other people involved already know and believe to be true, the speaker is viewed as more credible because it reinforces established beliefs. This positive reception encourages all parties to continue to offer up similar common information, pushing unique perspectives and differences of opinion into the background. Overall, this creates what psychologists Garold Stasser and William Titus call “hidden profiles” of problems under discussion: unique information remains unshared and hidden from most of the group. These dynamics played out between Britain and the US during Suez.

The Suez crisis shows that a group of political leaders cannot assume a comprehensive picture of adversaries and threats will emerge simply because there is a diverse set of viewpoints present during allied deliberations. The bias towards common rather than unique information must be accounted for as well. Because Eden had assumed Eisenhower shared his fears about Nasser, just as US officials presumed the unique views they withheld were in fact known in London, the PM was taken by surprise when the US acted against British interests.