Construction of the Central Line's eastern extension was started in the 1930s, and the tunnels were largely complete at the outbreak of the Second World War. While some stretches were used as underground factories, Bethnal Green station was used as an air-raid shelter, unofficially at first, and then with official blessing.
By 1943 the numbers using the station as a shelter had dwindled, only rising when retalliatory bombing in response to British raids was expected. This was the case on March 3, 1943, as the British press had reported a heavy raid on Berlin on the night of March 1. The air-raid warning sounded at 8:17 pm, causing an orderly flow of people down the short flight of steps into the underground booking office. At 8:27 an anti-aircraft battery a few hundred yards away in Victoria Park launched a salvo of a new type of anti-aircraft rockets. The weapon was secret, and the unexpected, unfamiliar type of explosion caused a panic. As the crowd surged forward towards the shelter, a woman, possibly carrying a baby, tripped on the stairs, causing many others to fall. Within a few seconds 300 people were crushed into the tiny stairwell. 172 people were dead at the scene, with one more dying in hospital later; 69 of the dead were children.
The government is accused of having "hushed up" the disaster, though several articles about it (omitting the precise location) were published in The Times. An inquiry was held, though its report was not made public until after the end of the war. It concluded that the poor lighting, lack of a crash barrier (which the local council couldn't afford to erect), and lack of supervision by police or ARP wardens had contributed to the disaster.
The crush at Bethnal Green is the largest loss of life in a single incident on the London Underground network. The largest number killed by a wartime bomb was 68 at Balham; the largest number killed in peacetime was 43 in the crash at Moorgate in 1975.