Did nuclear weapons help to make the world safer between 1945 and 1951?

Mushroom cloud produced by the detonation of XX-28 George, a 225-kiloton nuclear bomb, on 8 May 1951. XX-28 George was one of the first tests of thermonuclear fusion and was a purely experimental device. (US DEPARTMENT OF ENERGY/SCIENCE PHOTO LIBRARY, 680804817, Getty images)

In May 1945, the German surrender ended the Second World War in Europe. However, the war against Japan was still being fought. At the Potsdam Conference in July 1945, the US President, Harry Truman, informed Churchill that the Americans had successfully detonated an atomic bomb in the New Mexico desert. Churchill had already agreed with the USA that this new weapon should be used against Japan.

On 6 August, the US Air Force dropped an atomic bomb (equivalent to 12,500 tons of TNT) on the city of Hiroshima in Japan. A second bomb (with the power of 22,000 tons of TNT) was used against Nagasaki on 9 August. On 14 August, Japan surrendered. The combined death toll was over 100,000, with thousands more dying in the months and years that followed from burns, injuries and radiation-related illnesses.

A number of key developments in the years following 1945 made the appearance of such destructive weapons even more serious. Primarily, just as the Second World War was ending, the possibility of another conflict – against Stalin’s communist USSR – was posing a much more real threat. By mid-1945, USSR forces occupied much of Eastern and Central Europe, including half of Germany, and Britain and the USA worried that Stalin was determined to carve out a sphere of domination. At the Potsdam Conference, Truman casually remarked to Stalin that the USA had acquired a bomb of ‘unusual destructive force’. Some historians argue that the dropping of the Atomic Bomb on Japan was carried out mainly to impress the USSR with America’s new military might and therefore to strengthen the USA’s ability to negotiate with the Soviets over the future of Eastern Europe. Although he didn’t reveal it to Truman, Stalin already knew via his spies about the Americans’ Atomic Bomb, and was determined to develop a Soviet equivalent as soon as possible.

The years 1949–1950 saw this situation intensify. In August 1949, the USSR successfully tested its first atomic weapon. Two months later, Mao Zedong’s communist forces won a civil war in China. The global balance of power seemed to have shifted in favour of the communist bloc. In 1950, communist North Korea, supported by communist China and the USSR, invaded democratic South Korea. The USA and its allies immediately came to South Korea’s aid. Chinese troops, with weapons and other support from the USSR, were sent to help the North Koreans. For a while there seemed to be a real danger of nuclear warfare, after the US commander General Douglas MacArthur called for nuclear weapons to be used against China. President Truman sacked him, but many people in the USA felt that MacArthur was right.

Throughout the 1950s, the threat of nuclear war was always present. Both sides built up huge stocks of nuclear weapons. To many people at the time, the threat of a global and nuclear war was very real. Many historians argue, however, that with the stakes so high, the two sides actually went out of their way to avoid armed conflict (although there were many tense moments when open war seemed likely). As Churchill put it, ‘When the advance of destructive weapons enables everyone to kill everybody else, nobody will want to kill anybody at all’ (House of Commons, 3 November 1953). In this way, nuclear weapons were a deterrent and actually ensured peace, or at least prevented war between the superpowers.

 Investigation page

 The sources

 Notes for teachers

The "Baker" explosion, part of Operation Crossroads, a nuclear weapon test by the United States military at Bikini Atoll, Micronesia, on 25 July 1946. (United States Department of Defense (either the U.S. Army or the U.S. Navy), Wikimedia Commons)

Find out more

 Kevin Ruane on Churchill and Nuclear Weapons from the Churchill Archive*
 Kevin Ruane on the Cold War and Nuclear Weapons from the Churchill Archive*
 Nuclear Power: The End of the War Against Japan from BBC History
 BBC History website on the Cold War
 National Archives classroom resources on the Cold War

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