The UK-US relations in World War II comprised an extensive and highly complex relationship, in terms of diplomacy, military action, financing, and supplies. British Prime Minister Winston Churchill and American President Franklin D. Roosevelt formed close personal ties, that operated apart from their respective diplomatic and military organizations against Hitler's Germany, Mussolini's Italy and Tojo's Japan.

Leadership issues While Franklin Roosevelt and Winston Churchill have thoroughly dominated the popular and scholarly writings, each stood atop a complex decision-making system that guaranteed inputs from military, diplomatic, business and public opinion.

In terms of foreign-policy, Roosevelt for years had developed a system whereby he made all the major decisions.Warren F. Kimball, "Franklin D. Roosevelt and World War II," Presidential Studies Quarterly 34#1 (2004) pp. 83–99. online Secretary of State, Cordell Hull was relegated to ceremonial roles.Julius W. Pratt, "The Ordeal of Cordell Hull." Review of Politics 28.1 (1966): 76–98. online Secretary of the Treasury Henry Morgenthau Jr. had the loudest voice in financial matters, and was deeply engaged in foreign policy, especially regarding Lend Lease, China, Jews and Germany. Although Roosevelt himself was quite pragmatic about moral issues, the image he presented to outsiders, especially the British, grated on their sensibilities. British foreign minister Anthony Eden told his war cabinet, "Soviet policy is amoral; United States policy is exaggeratedly moral, at least where non-American interests are concerned."Robert Rhodes James, 'Anthony Eden: A Biography (1986) p 264

In military affairs, the Joint Chiefs of Staff was headed by Admiral William D. Leahy, a close personal friend of the president for decades. It dealt directly with their British counterparts in a new organization, the Combined Chiefs of Staff, which was based in Washington. Military decisions were made through the joint Chiefs and the combined chiefs, and they issued the orders to the theatre chiefs. The chiefs were in command of all Allied forces in their geographical zone. This was a new concept in military history, one promoted by General Marshall and accepted reluctantly at first by the British. In terms of British-American military teamwork, the key theaters were the Mediterranean and the West European – SHAEF. US general Dwight D. Eisenhower Headed the Mediterranean Theater 1943–44, then moved to SHAEF.Forrest Pogue, The Supreme Command (1954) pp. 56–65 online

Historians have always paid special attention to the Roosevelt-Churchill friendship. They also have explored how the two men dealt with Joseph Stalin, the Soviet dictator.Herbert Feis, Churchill-Roosevelt-Stalin: The War they waged and the Peace they sought (1957).William Hardy McNeill, America, Britain, and Russia: their co-operation and conflict, 1941–1946 (1953) Roosevelt and Churchill met in person 11 times. They exchanged 1700 cables and letters and they even made some international phone calls. Roosevelt also sent top aides, especially Harry Hopkins and to a lesser extent W. Averell Harriman.Robert E. Sherwood, Roosevelt and Hopkins (1948) Harriman accompanied Churchill to the Moscow Conference in 1942 to explain to Stalin why the western allies were carrying out operations in North Africa instead of opening the promised second front in France. Harriman was appointed as Ambassador to the USSR in 1943.W. Averell Harriman, Special Envoy to Churchill and Stalin, 1941–1946 (1975).

Churchill ran a coalition government, with all parties represented. He dominated his War Cabinet. Clement Attlee, the leader of the Labour party, was Deputy Prime Minister and handled practically all domestic affairs. He did so very quietly, usually backstage. Churchill, like Roosevelt, relied on charisma and a very strong public image, to rally public opinion. Churchill handled all the top foreign policy decisions himself, with his Foreign Minister Anthony Eden taking charge only of lower visibility issues.James, Anthony Eden (1986) p 247 Churchill made himself Minister of Defence and repeatedly interfered and reshaped and argued with his chiefs of staff. Historians generally agree with the quality of Churchill's wartime leadership, often emphasizing his remarkable success in obtaining American support. Richard Wilkinson, who is more critical than most historians, nevertheless argues: No one else in Britain could have approached Churchill's achievement in winning the support of President Roosevelt and his fellow citizens....He displayed a profound and sincere admiration for America. His courtship of Roosevelt was a marvellous mixture of flattery, bonhomie, and the reiteration of those values which the USA and Great Britain shared and therefore of the threat which Nazism posed to both democracies. Churchill appealed to America's interests and to her sentiments.Richard Wilkinson, "Winston As Warlord: A Critical Appreciation." History Review (2011), Issue 71, pp. 26–31.

The British sent two ambassadors to Washington; each achieved very positive reputations for handling American leaders and influencing American public opinion.H.C. Allen, Great Britain and the United States (1954) pp. 787–789. Lord Lothian served in 1930–40. On his death Lord Halifax took charge, 1940–46. Halifax as Foreign Minister (1938–40) had been a leader of the appeasement movement before 1939, but then reversed himself and took an aggressive anti-Hitler position. The US Ambassador 1938–40 Joseph P. Kennedy was a defeatist who in 1940 warned Roosevelt that Britain was doomed. Roosevelt could not remove Kennedy because he needed Irish support in the major cities in the 1940 election, Kennedy endorsed Roosevelt then retired, to be replaced by low-key Republican John Winant, who did well in London, 1941–46.David Mayers, FDR's Ambassadors and the Diplomacy of Crisis: From the Rise of Hitler to the End of World War II (2013)Bert R. Whittemore, "'A Quiet Triumph': The Mission of John Gilbert Winant to London, 1941." Historical New Hampshire 30 (1975): 1–11.

After the declarations of war, foreign-policy issues were no longer high on the political agenda. Appeasement was dead in Britain; isolationism was dead in the United States. After the U.S. entered the war in December 1941, foreign-policy was rarely discussed by Congress, and there was very little demand to cut Lend Lease spending. In spring 1944, the House passed a bill to renew the Lend Lease program by a vote of 334 to 21. The Senate passed it by a vote of 63 to 1.H.G. Nicholas, ed., Washington Dispatches 1941–1945: Weekly Political Reports from the British Embassy (1981) pp. 113, 148, 238, 262, 338, 351, 359

Top level conferences Atlantic Charter 1941 Roosevelt and Churchill met secretly at Placentia Bay in Newfoundland in August 1941, and issued a policy statement that became the foundation document for the Allies who later joined the war against Germany. A country had to join to gain admission to the United Nations. The Atlantic Charter defined the Allied goals for the post world war. The Charter stated the ideal goals of the war—no territorial aggrandizement; no territorial changes made against the wishes of the people, self-determination; restoration of self-government to those deprived of it; reduction of trade restrictions; global cooperation to secure better economic and social conditions for all; freedom from fear and want; freedom of the seas; and abandonment of the use of force, as well as disarmament of aggressor nations. Adherents of the Atlantic Charter signed the Declaration by United Nations on 1 January 1942, which became the basis for the modern United Nations. The Charter was a powerful propaganda weapon, but Churchill, profoundly committed to maintaining British Empire, claimed it did not apply to British possessions.Theodore A. Wilson, The First Summit: Roosevelt and Churchill at Placentia Bay, 1941 (1991) excerpt Churchill's insistence on full control was signaled when he did not bring along his foreign minister Anthony Eden.James, Anthony Eden p 247

Arcadia, 1941–1942

The Arcadia Conference was held in Washington, from December 22, 1941 to January 14, 1942, bringing together the top British and American military leaders. Churchill and Roosevelt and their aides had very candid conversations that led to a series of major decisions that shaped the war effort in 1942–1943.David Jay Bercuson and Holger H. Herwig, One Christmas in Washington: Roosevelt and Churchill forge the grand alliance (2006), online free The decision was made to invade North Africa in 1942, to send American bombers to bases in England, and for the British to strengthen their forces in the Pacific. The Conference established the Combined Chiefs of Staff, headquartered in Washington, which approved and finalized all military decisions. It also created a unified American-British-Dutch-Australian Command (ABDA) in the Far East; it fared poorly. Finally the conference drafted the Declaration by United Nations, which committed the Allies to make no separate peace with the enemy, and to employ full resources until victory.William Hardy McNeill, America, Britain and Russia: Their Cooperation and Conflict 1941–1946 (1953) pp 90–118

Quebec Conference, 1943 At the Quebec Conference, 1943 held in Canada in August 1943, Churchill, Roosevelt and the Combined Chiefs plotted strategy against Germany. They began planning the invasion of France, codenamed Overlord using a report by the Combined Chiefs. They also discussed an increase of the bombing offensive against facilities Germany was using in France and the Low Countries. They decided to continue the buildup of American forces in Britain prior to an invasion of France. Churchill kept drawing attention to the advantages of operations in the Mediterranean theatre. They agreed to use more force to force Italy out of the war, and to occupy it along with Corsica. Military cooperation was close and successful. The Prime Minister of Canada was the host, but no Canadians attended the secret meetings.Charmley. Churchill's Grand Alliance: The Anglo-American Special Relationship 1940–57 (1996)

Casablanca Conference 1943

From January 14–24, 1943 Roosevelt, Churchill and the Combined Staff met in Casablanca, Morocco. They decided on the major Allied strategy for 1943 in Europe, especially the invasion of Italy and planning for the invasion of France. They blended British and American offensive concepts.Brian P. Farrell, "Symbol of Paradox: The Casablanca Conference, 1943." Canadian Journal of History 28.1 (1993): 21–40. At Roosevelt's demand, they agreed on a policy of "unconditional surrender." This policy uplifted Allied morale, but it also made the Nazis resolve to fight to the bitter end.Alan F. Wilt, "The Significance of the Casablanca Decisions, January 1943," Journal of Military History (1991) 55#4 pp 517–529 in JSTOR A major problem was to establish a working relationship between the two main French allies, Henri Giraud, the French high commissioner in North Africa, and General Charles de Gaulle, leader of the Free French. Roosevelt strongly disliked de Gaulle, while Churchill championed him. The final decision was to split control of liberated French areas between the two Frenchmen. By 1944, de Gaulle prevailed, but he never forgave Roosevelt and always distrusted Anglo-American collaboration as hostile to French interests.Arthur Layton Funk, "The 'Anfa Memorandum': An Incident of the Casablanca Conference." Journal of Modern History 26.3 (1954): 246–254. online

Lend-Lease