From 7 September 1940, one year into the war, London was bombed by the Luftwaffe for 57 consecutive nights. More than one million London houses were destroyed or damaged and more than 40,000 civilians were killed, almost half of them in London. Ports and industrial centres outside London were also attacked. The main Atlantic sea port of Liverpool was bombed, causing nearly 4,000 deaths within the Merseyside area during the war. The North Sea port of Hull, a convenient and easily found target or secondary target for bombers unable to locate their primary targets, was subjected to 86 raids in the Hull Blitz during the war, with a conservative estimate of 1,200 civilians killed and 95 percent of its housing stock destroyed or damaged. Other ports including Bristol, Cardiff, Portsmouth, Plymouth, Southampton and Swansea were also bombed, as were the industrial cities of Birmingham, Belfast, Coventry, Glasgow, Manchester and Sheffield. Birmingham and Coventry were chosen because of the Spitfire and tank factories in Birmingham and the many munitions factories in Coventry. The city centre of Coventry was almost destroyed, as was Coventry Cathedral.