Battles & Wars › Between the wars › World War II
Franklin D. Roosevelt
1882–1945; president 1933–45· Person· Americas
Well documentedSolid records, physical evidence or scientific consensus.
Four-term US president who led America through the Great Depression and most of World War II, and held the Allied coalition together.
See it on the Battles & Wars map →What happened
Elected in 1932 amid the Depression, Roosevelt launched the New Deal. As war spread, he edged a neutral US toward Britain: destroyers for bases in 1940, the 'Arsenal of Democracy' speech, Lend-Lease in March 1941. After Pearl Harbor he backed a 'Germany first' strategy with Churchill, met Churchill and Stalin at Tehran (1943) and Yalta (February 1945), and approved the Manhattan Project. Paralyzed from the waist down by illness since 1921, he died on April 12, 1945, weeks before Germany surrendered.
Why it matters
He turned US industrial power into Allied victory and shaped the postwar order, including the United Nations, which he pushed for but did not live to see.
Legacy and how we know
Legacy: the only president elected four times, which led to the 22nd Amendment's two-term limit. Known from his presidential library at Hyde Park, recorded fireside chats, government papers and his Churchill correspondence.
Still debated
Historians still argue over Yalta: whether a dying Roosevelt conceded too much in Eastern Europe, or simply accepted what the Red Army already held.
Connections (5)
▸Franklin D. Roosevelt led America's response to Attack on Pearl HarborWell documented
The connection
The day after the attack, Roosevelt asked Congress to declare war on Japan, calling December 7 'a date which will live in infamy'. Congress agreed with one vote against. When Germany declared war on the US on December 11, he committed to defeating Germany first while building up forces for the Pacific.
When and how
Washington, December 8, 1941, before a joint session of Congress; Representative Jeannette Rankin cast the only vote against war.
How we know
The speech recording, the Congressional Record and Roosevelt's papers document the response.
Debates and open questions
Historians debate whether US pressure, especially the 1941 oil embargo, pushed Japan toward war sooner than Roosevelt expected.
▸Franklin D. Roosevelt authorized Manhattan ProjectWell documented
The connection
In October 1939 Roosevelt received a letter signed by Albert Einstein, drafted with physicist Leo Szilard, warning that Germany might build an atomic bomb. He set up a uranium committee, approved an all-out effort in late 1941, and in 1942 the Army took it over as the Manhattan Project, which spent about $2 billion in secret.
When and how
White House, October 11, 1939, when economist Alexander Sachs delivered the letter; full program approved October 1941; Manhattan Engineer District created August 1942.
How we know
The Einstein–Szilard letter and Roosevelt's reply survive at the FDR Library; project records were declassified after the war.
Debates and open questions
Roosevelt left little record of how he intended the bomb to be used; what he would have decided in 1945 is unknown.
▸Franklin D. Roosevelt forged a wartime alliance with Winston ChurchillWell documented
The connection
Roosevelt and Churchill exchanged well over a thousand letters and telegrams and met repeatedly, first as wartime leaders at sea off Newfoundland in August 1941, where they issued the Atlantic Charter. They agreed on Germany first, on landings in North Africa, and later on Normandy. The partnership was close but unequal, and they clashed over empire and strategy.
When and how
Placentia Bay, Newfoundland, August 1941; then Washington, Casablanca, Quebec, Cairo, Tehran and Yalta, 1941–45.
How we know
Their complete correspondence, edited by historian Warren Kimball, and the conference records are published.
Debates and open questions
Historians debate how much Roosevelt valued Britain versus planning a postwar world without its empire, and how far he leaned toward Stalin at Tehran.
▸Franklin D. Roosevelt met at Tehran and Yalta with Joseph StalinWell documented
The connection
Roosevelt and Stalin first met at Tehran, with Churchill, where Stalin won a firm date for the invasion of France and promised to fight Japan after Germany's defeat. At Yalta they agreed on occupation zones in Germany and the United Nations; Stalin pledged war on Japan in return for land in Asia, and promised free elections in Poland.
When and how
Tehran, Iran, November 28 – December 1, 1943; Yalta, Crimea, February 4–11, 1945; with Winston Churchill and their interpreters.
How we know
Official minutes and interpreters' notes, published in the US Foreign Relations series and in Soviet records, and memoirs by Churchill and others.
Debates and open questions
Critics say an ailing Roosevelt gave away Eastern Europe at Yalta; defenders reply the Red Army already held it. Roosevelt also informally proposed a trusteeship for Korea there.
▸Arsenal of Democracy: US war production was named in a fireside chat by Franklin D. RooseveltWell documented
The connection
On December 29, 1940, in a radio 'fireside chat', Roosevelt told Americans that Britain's survival mattered to US security and that 'we must be the great arsenal of democracy'. The phrase framed US industry's role before the country was at war, and prepared the ground for Lend-Lease.
When and how
The White House, December 29, 1940; Roosevelt, with speechwriters Robert Sherwood and Harry Hopkins.
How we know
The speech text and recording survive at the FDR Library.
Debates and open questions
The phrase's origin is disputed: it is credited to French official Jean Monnet, among others, and had been used before the speech.