From September 1940 to May 1941, the German Luftwaffe bombed London and other British cities almost every night in a sustained attack called the Blitzkrieg, or “lightning war.”

The Blitz was meant to cripple Britain’s war production and demoralize the population into surrender.

Londoners sought protection in their homes, in their yards, and even in the stations and tunnels of the London Underground.

The government was initially wary of using the stations as shelters, concerned that the thousands congregating underground below the ferocious bombing would refuse to return to the surface and take up the work necessary to keep the country running. As more and more people lost their homes, the government relented and allowed people to shelter in the stations, even outfitting some with bunk beds.

Sleeping on platforms and in trains and service tunnels with hundreds of others was far from a spirited slumber party. Sanitation and latrines were inadequate for such large numbers of people.

Even the stations were not completely safe. On Oct. 14, 1940, a 3,000-pound bomb struck Balham Station, rupturing gas and water lines and killing 66 people inside.

In the eight months of the Blitz, more than 43,000 civilians were killed, 140,000 wounded, and a million homes destroyed or damaged.