 Between 25 and 31 July, 32 Soviet ships were sunk, with another nine crippled.The battle began with the heavy bombing of the city by "Generaloberst" Wolfram von Richthofen's "Luftflotte 4", which in the summer and autumn of 1942 was the single most powerful air formation in the world.Some 1,000 tons of bombs were dropped in 48 hours, more than in London at the height of the Blitz.