Starting on 5 September 1940, Blenheims of Bomber Command began a bombing campaign targeting German-occupied ports along the English Channel, alongside heavier bomber types. Bomber Command Blenheims also performed anti-shipping patrols due to Coastal Command's own strike squadrons being heavily depleted throughout the latter half of 1940. On 11 March 1940, a Blenheim IV, "P4852", became the first RAF aircraft to sink a U-boat, having scored two direct hits on U-31 in the Schillig Roads. In April 1941, a campaign aiming to completely close off the Channel to enemy shipping was launched using an initial flight of Blenheims stationed at RAF Manston. Between April and June that year, a total of 297 Blenheims of No 2. Group attacked German shipping at sea, losing 36 aircraft, while Coastal Command launched 143 attacks in the same period, losing 52 aircraft; by the end of the year, 698 ships had been attacked and 41 of these sunk for the loss of 123 aircraft.