In April 1941 the Midlands bore the brunt of German bombing raids with only three nights respite, 75 percent of them carried out by Sperrle's air fleet. Birmingham was bombed on consecutive nights by 237 and 206 aircraft. Coventry was also subjected to a 237-bomber attack. British ports were also targeted as part of 16 major and five heavy attacks. Plymouth, Glasgow and Belfast were bombed in mid-April and morale was severely effected. Plymouth was bombed on five of the eight nights from 21 to 30 April by 120, 125, 109, 124 and 162 aircraft. The Port of London was bombed by 685 aircraft on 16 April and by 712 on 20 April. April was the most intensive month of the Blitz for "Luftflotte" 3 in 1941—approximately 3,750 bombing operations in comparison to 1,500 by Kesselring's air fleet.