1 June, three of the squadron's Ansons were patrolling off Dunkirk when they came under attack by as many as nine German Messerschmitt Bf 109 fighters. The Ansons had been modified to improve their armament by adding two beam machine guns, and one of the Ansons claimed two Bf 109s shot down. While the squadron further modified the armament of some of its Ansons in August for use against German E-boats by adding a 20 mm cannon firing through the floor, it was increasingly deployed on convoy escort duties. In April 1941 the Ansons were replaced with Bristol Blenheims which were deployed on anti-shipping and air-sea rescue duties, as well as night intruder operations over German-occupied Europe. The squadron moved from Detling to RAF Bircham Newton in May that year and converted to Lockheed Hudsons in November 1941. In March 1942, the squadron moved to RAF Stornoway in Scotland, with detachments at Limavady in Northern Ireland for anti-submarine patrols over the Western Approaches. It moved again in at the end of August to RAF St Eval in Cornwall, but this was only a brief stopover before moving to Gibraltar on 5 November 1942 in preparation for the Allied invasion of French North-West Africa. Mediterranean operations The Allied landings saw 500 Squadron being very heavily deployed to protect the invasion shipping, making many attacks against German submarines attempting to interfere with the landings. On 8 November, half of the 500 Squadron ground crew landed along the beaches of Algeria, Oran and Arzeu, after having been dispatched to the Clyde River to board the SS Strathallan. The Strathallan made a second trip, also carrying 500 Squadron members but was sunk by a U-boat off Oran. Meanwhile, also on the first day of the landings, the squadron flew patrols in their newly painted, desert colours, Hudsons. These were mainly over the invasion beaches at Oran, with one of its Hudsons slightly damaged by gunfire from a German Heinkel He 111 bomber. On 11 September the Squadron established an advanced base at Tafraoui near Oran, Algeria, and on the same day, one of the squadron's Hudsons claimed a Junkers Ju 52 transport shot down near Alboran Island. On 13 November, a 500 Squadron Hudson attacked the German submarine U-458 with depth charges and machine gun fire, badly damaging it and forcing it to return to base. The next day, six 500 Squadron Hudsons attacked