During the period of the phoney war the He 111 was tasked with strategic bombing attacks over the North Sea and naval bases in the United Kingdom as a means of attacking the Royal Navy. On 9 November 1939, Adolf Hitler issued directive No. 9 which emphasised the target with most importance as the British navy. Mindful of the damaging blockade that hurt the German war effort in the First World War, the directive selected British port storage depots with particular reference to oil and grain facilities, mining British sea lanes and direct attacks on British merchant shipping.