The Bristol Blitz was the heavy bombing of Bristol, England by the Nazi German Luftwaffe during the Second World War. Due to the presence of Bristol Harbour and the Bristol Aeroplane Company, the city was a target for bombing and was easily found as enemy bombers were able to trace a course up the River Avon from Avonmouth using reflected moonlight on the waters, into the heart of the city. Bristol was the fifth-most heavily-bombed British city of the war.

World War II (1939–1945) involved sustained strategic bombing of railways, harbours, cities, workers' and civilian housing, and industrial districts in enemy territory. Strategic bombing as a military strategy is distinct both from close air support of ground forces and from tactical air power. During World War II, many military strategists of air power believed that air forces could win major victories by attacking industrial and political infrastructure, rather than purely military targets. Strategic bombing often involved bombing areas inhabited by civilians, and some campaigns were deliberately designed to target civilian populations in order to terrorize them and disrupt their usual activities. International law at the outset of World War II did not specifically forbid the aerial bombardment of cities – despite the prior occurrence of such bombing during World War I (1914–1918), the Spanish Civil War (1936–1939), and the Second Sino-Japanese War (1937–1945).