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.

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.

[2] 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.

"[3] In military affairs, the Joint Chiefs of Staff was headed by Admiral William D. Leahy, a close personal friend of the president for decades.

[8] 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.

Clement Attlee, the leader of the Labour party, was Deputy Prime Minister and handled practically all domestic affairs.

Historians generally agree with the quality of Churchill's wartime leadership, often emphasizing his remarkable success in obtaining American support.

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.

[15] 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.

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.

[17] 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.

[18] 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.

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.

[19] At the Quebec Conference, 1943 held in Canada in August 1943, Churchill, Roosevelt and the Combined Chiefs plotted strategy against Germany.

[23] The Americans spent about $50 billion on Lend Lease aid to the British Empire, the Soviet Union, France, China, and some smaller countries.

It received back about $7.8 billion in goods and services provided by the recipients to the United States, especially the cost of rent for American installations abroad.

[25] The question of repayment came up, and Roosevelt repeatedly insisted the United States did not want a postwar debt problem of the sort that had troubled relations after the first world war.

It set all the major policy decisions for the two nations, subject to the approvals of Prime Minister Winston Churchill and President Franklin D Roosevelt.

Catalyzed by the Tizard Mission, the two nations shared secrets and weapons regarding the proximity fuze and radar, as well as airplane engines, Nazi codes, and the atomic bomb.

There was a large pacifist element, which rallied to Gandhi's call for abstention from the war; he said that violence in every form was evil.

In 1942 when the Congress Party launched a Quit India Movement of nonviolent civil disobedience, the Raj police immediately arrested tens of thousands of activists (including Gandhi), holding them for the duration.

Meanwhile, wartime disruptions caused severe food shortages in eastern India; hundreds of thousands died of starvation.