What+caused+the+Blitz?

The whole thing started on a normal day in world-war 2, in fact it was August the 25th, 1940, when a lost German pilot accidentally bombed a central London factory. The British decided to retaliate by launching a bombing strike on Berlin the next night. Hitler was incensed and issued orders to launch a unforgiving bombing campaign against London. On September 7, the London Blitz began.