In 1939, Britain enacted a manmade blackout, a drastic measure taken to make it harder for German air forces to bomb the city's most populous cities. Because the UK government feared a nighttime attack, it mandated draining the light from Britain's cities to make them a harder target. In preparation for the blackout, which Mashable recently published wonderful photo essay about, cities dispatched workers to paint white markings on curbs to aid pedestrians and drivers. Car headlights were fitted with slotted covers that deflected the beams downward, and drivers had to obey a new 20-mile-per-hour speed limit. Many shopkeepers installed double doors, similar to those used in a photo darkroom, so that customers could leave without any light escaping. The blackout in the U.K. lasted for nearly six years, until the day Hitler committed suicide in April 1945.