The High Commissioner to Palestine warned officials in London that the "bitterness evoked" by events on board the SS Exodus in 1947 should not be underestimated.
The extent of the damage to relations between the Jews and their British rulers as a result of the decision to force those on board – many of them Holocaust survivors - to return to Europe is made clear in a series of newly-released intelligence reports from the colonial era.
"The Yishuv has followed events… with close attention," said one report, authored by Sir Alan Cunningham, then the British High Commissioner, noting the end to "the intermission in illegal immigration".
He wrote: "The intransigent attitude of the passengers has been applauded… Meanwhile the Hebrew press seizes every opportunity to use this incident as a stick with which to beat the Palestine Administration and His Majesty's Government, and to sustain the bitterness which the deportation undoubtedly aroused."
The ship, which was originally named the President Warfield and was referred to as such in the intelligence reports, is the most famous example of the illegal immigration that occurred in the years before independence, as Zionist groups sought to bring refugees from Holocaust-ravaged Europe to Palestine.
Their efforts were opposed by the British, with refugees held in camps in Atlit and Cyprus.
The Exodus set sail on July 11, but when it approached the Mediterranean coast of Palestine, British forces seized it. Three people died and those aboard were forcibly returned to Europe, at which point they declared a hunger strike. It was a public relations disaster for the British, but it still resulted in the Jewish refugees being transferred to displaced persons camps in Germany.
Another report reveals how the decision to return the illegal immigrants on the ship to France "undoubtedly caught the [Jewish] Agency unaware, and the successful preservation of secrecy until the transports were well on their way probably prevented a sharper reaction by the Yishuv [the Jewish community].
"Nevertheless the bitterness evoked by this departure from practice must not be underestimated," the report stated. "The Arabs are naturally gratified."
The High Commissioner noted that the decision to permit pregnant women to disembark at Gibraltar had been "met with little appreciation" and reported that the Yishuv signalized its solidarity with the refugees "by observing a day-long fast, which passed off uneventfully."
In a sign of the divide between the establishment and the Haganah, Sir Alan also said that the Jewish Agency had been "at particular pains to emphasize that it was not Zionist propaganda which had induced those on board the transport to refuse disembarkation in France".
The incident, later immortalised by Leon Uris, was a turning point in attitudes towards the Zionist cause, as photographs and reports were seen around the world. But it did not dispose the British towards easing restrictions; a report from later that year discussed use of force while searching rebellious detainees in Athlit, with the comment "In fact no greater degree of force was used than was needed to overcome opposition to the search".
It also details the methods used by Jewish detainees to evade their British guards. "When the camp was searched a number of pistols, bombs and uniforms were found, which had apparently been introduced into the camp in the false bottoms of food boxes supplied by the officially-recognised Jewish Prisoners Aid Society," explained one briefing. "In consequence visitors and food parcels have been stopped."