10 July, the official first day of the Battle of Britain, witnessed increased aerial activity over the English Channel and along the eastern and southern seaboards of the British coastline. The main assaults by ever-increasing formations of Luftwaffe bombers, escorted by Bf 109 and Bf 110 fighters, were initially aimed at British merchant shipping convoys plying their trade of coal and other materials from the north of England to the southern ports.
These attacks often met with increasing success although RAF Spitfires and Hurricanes endeavoured to repel the Heinkel He 111s, Dornier Do 17s and Junkers Ju 88s, frequently with ill-afforded loss in pilots and aircraft. Within a month, the English Channel was effectively closed to British shipping.
Only a change in the Luftwaffe’s tactics in mid-August, when the main attack changed to the attempted destruction of the RAF’s southern airfields, allowed convoys to resume sneaking through without too greater hindrance.