http://www.onwar.com/chrono/1941/sep41/f20sep41.htm
Italian midget subs strike Gibraltar
Saturday, September 20, 1941 www.onwar.com
In the Mediterranean... Italian midget submarines attack shipping in the harbor at Gibraltar and sink two ships.
In the North Atlantic... Heavy losses in convoys continue, but an aircraft from the British escort carrier, Audacity downs a Folfwolf Condor trying to shadow the convoy OG-74. This is the first time the carrier based aircraft have had a successful kill.
http://homepage.ntlworld.com/andrew.etherington/month/thismonth/20.htm
September 20th, 1941
ATLANTIC OCEAN: Convoy OG-74 is sailing with escort carrier HMS Audacity in the escort. Today an aircraft, from Audacity, downs a FW-Condor shadowing the convoy. 6 of 27 ships in the convoy are lost during the crossing.
Whilst escorting convoy SC.44, Flower class corvette HMS Levis is torpedoed and sunk by U-74 South of Ireland at 60 07N 38 37W. Levis sinks within a minute of the torpedo striking. (Alex Gordon)(108)
GIBRALTAR: Italian midget submarines attack shipping in the harbour. They sink 2 ships.
Led by Prince Giunio Borghese, three two-man submarines, penetrated the defences and sank 20,000 tons of shipping. Their mother ship is a converted submarine, moored off the Spanish coast. All the frogman returned safely.
MALTA: The first ‘Hurribomber’ Hawker Hurricane fighter-bomber conversions go into service today. They can carry two 250-lb bombs. (22)
FRANCE: Paris: A curfew is imposed between 9pm and 5am.
While flying an offensive sweep over Northern France, the pilots of No. 452 Squadron, RAAF, equipped with Spitfire Mk. VBs and based at Kenley, Surrey, England, claims seven Luftwaffe Bf 109s shot down and two damaged. (Jack McKillop)
UNITED KINGDOM: Enigma decodings give Britain and the USSR advance warning of an all-out German assault on Moscow.
The first successful sortie by the photo-reconnaissance variant of the de Havilland Mosquito was made today when W 4055 (LY-T) of the RAF Photographic Development Unit based at RAF Benson flew a daylight reconnaissance over Brest, La Pallice and Bordeaux, returning over Paris. Although it was chased by three Messerschmitt Me 109 fighters, the Mosquito easily outpaced them at 23,000 ft. (22)
Babyn Yar massacre by the Einsatzgruppen happened soon afterwards.