It is a letter that might have changed the course of European history- had it been sent. In early June 1944, a vast armada was gathering on the south coast of England with the task of liberating France and, despite concerns about leaks from the French camp, the British prime minister, Winston Churchill, had invited Gen Charles de Gaulle to fly to London on his personal plane from Algiers. On his arrival in Britain, De Gaulle, the leader of the free French, had been let in on the seismic events that would unfold within hours – the D-day landings on the beaches of Normandy which took place 80 years ago next week. But things did not go to plan. An exasperated Churchill, fuming in his Downing Street study, put pen to paper, just hours before the invasion would be under way, to draft a letter that would surely end De Gaulle’s political career. In the letter, discovered among papers held at the National Archives in Kew ahead of 80th anniversary commemorations in France next week, he chastises De Gaulle for not wanting to broadcast a speech ahead of the landings and for blocking the dispatch of French liaison officers to accompany the allied troops into France. The general relented – at least in part – on both these points and so the two-page missive was never sent. But Churchill’s fury at the time of writing is made clear. He condemns “the heinous character of [De Gaulle’s] action” and threatens to “make plain to the world that the personality of General de Gaulle is the sole and main obstacle between the great democracies of the west and the people of France”. “General de Gaulle, I regret very much that you have refused to join with the other United Nations concerned in the broadcasts, which are to be delivered at the opening phases of this great and, in many ways, unique battle,” Churchill writes. “I have tried very hard on many occasions, during four years, to establish some reasonable basis for friendly comradeship with you. Your action at this juncture convinces me that this hope has no further existence.” Churchill continued: “If anything could make matters more clear it is your refusal to allow the 120 French liaison officers, who have been so carefully trained, to go with the Anglo-American armies into France and your order to them to desert the effort now being made for liberation. “Whatever course they may take in no way diminishes the heinous character of your action, and I find it my duty to tell you that at the first convenient opportunity, having regard to military operations, I shall make plain to the world that the personality of General de Gaulle is the sole and main obstacle between the great democracies of the west and the people of France, to whose rescue they are coming, no matter what the cost may be.” Churchill concluded the letter: “I can conceive no useful purpose in your staying longer and that the airplanes will be at your disposal tomorrow night, weather permitting.” Had it been sent, the vituperative letter would surely have marked a defining breach with the French Committee of National Liberation chaired by De Gaulle, which had aspirations of being the provisional government of a liberated France. However, before it was dispatched, the French leader did agree to give a speech on the Francophone service of the BBC, albeit later in the day than the allies had hoped. He also permitted 20 of the original 120 French liaison officers to join the allied forces as they stormed the beaches of Normandy. At the top of Churchill’s draft letter, in capital letters and in blue pencil, it is marked “NOT TO GO”. The episode offers a telling insight into the stormy relations between the allies, particularly the Americans and the French. The row on the eve of D-day had been prompted by a clash earlier in the day, not with Churchill but between De Gaulle and the supreme commander of the allied expeditionary force, Gen Dwight Eisenhower. De Gaulle had demanded a rewrite of Eisenhower’s own proposed D-day address after seeing it for the first time on 5 June. He wanted Eisenhower to say that the French authorities would re-establish civil rule, providing a role for what De Gaulle regarded as his provisional government, while the American general planned to commit to new elections when France was liberated. De Gaulle’s request was both unacceptable to the allies and it had come too late. The leaflets of Eisenhower’s broadcast, due to be distributed around Normandy, had already been printed. Back in the White House, the US president, Franklin Roosevelt, was adamant that De Gaulle should not be treated as France’s president until the French had spoken at the ballot box. That storm passed but relations would remain difficult for the duration of the war. Before the row, Churchill had agreed that De Gaulle might visit Normandy soon after the amphibious invasions. Writing to Gen Bernard Montgomery, commander of all allied ground forces during Operation Overlord, Churchill wrote apologetically on 13 June: “I must inflict upon you a visit from General de Gaulle tomorrow.” In a note to the foreign secretary at the time, Anthony Eden, Churchill further remarked: “Remember that there is not a scrap of generosity about this man, who only wishes to pose as the saviour of France in this operation without a single French soldier at his back. You know the reasons why we brought him over here and that they arose out of pure chivalry toward his unhappy country, to tell them about the battle before it was engaged; and that he thought we had only got him here to get him to make a broadcast supporting it.” In September 1944, De Gaulle returned to Paris and was recognised by the allies as the chair of the provisional French government. He resigned in 1946 claiming he lacked sufficient governing power. He only returned in 1958 to head a new emergency government after a revolt in Algeria led to a severe political crisis. De Gaulle, who died in 1970, maintained his fraught relationship with Britain for the rest of his career, vetoing UK’s applications to join the European economic community, the forerunner of the EU, in both 1963 and 1967. About a million people are expected to attend the D-Day commemorations in France on Wednesday and Thursday, including the US president, Joe Biden, and the Ukrainian president Volodymyr Zelenskiy. This article was amended on 31 May 2024. De Gaulle was the chair of the provisional French government, not the president; and he resigned in 1946, not 1948.