December 21st, 1943 (TUESDAY)
FRANCE: Eighty four USAAF Ninth Air Force B-26 Marauders bomb V-weapon sites and other targets.
During the night of 21/22 December, four RAF Bomber Command bombers drop leaflets over the country.
GERMANY: During the night of 21/22 December, RAF Bomber Command Mosquitos bomb four targets in two cities: in Dusseldorf, four bomb the Mannesmann steel factory and three hit the city; in Cologne, two bomb the city and one attacks the Knapsack power station.
U-874 launched.
ITALY : In the British Eighth Army's V Corps area, the Canadian 1st Division of the Eighth Army, meets stiff German resistance near Ortona. After finally crossing "the gully" the Canadians now believe that the town will come easily. The Germans have evacuated the Italian town and begin by blowing up a large part of it, the rubble blocking the Canadian tanks but leaving certain pathways that are now set up for killing fields. As the Canadians move in, the Germans set up booby traps everywhere. Even toilets might be death, or a purposefully left souvenir knife or such. Italian houses have common walls, so the Canadians can go in one, go to the top, blow a hole in the common wall, and descend on the Germans. This process is called "mouseholing." (John Nicholas and Gene Hanson)
The first elements of the Polish II Corps land at Taranto. They are commanded by Lieutenant General Wladyslaw Anders and Deputy Commander Lieutenant General Zygmunt Szyszko-Bohusz. (Alex Bielakowski)
USAAF Twelfth Air Force B-25 Mitchells bomb Terracina and P-40s hit the same target and also bomb positions and munitions factory south of Sant' Elia Fiumerapido. A-36 Apaches bomb positions, a fuel dump, and munitions factory in the Cervaro area, and hit trains, a seaplane base, a radar station, trucks, and other targets in the Rome-Civitavecchia area.
POLAND: Auschwitz-Birkenau: Hersh Kurcwaig and Stanislaw Dorosiewicz escape from the camp after killing a guard.
U.S.S.R.: The German bridgehead across the Dniepr River near Kherson is captured by the Russians.
BURMA: U.S. Lieutenant General Joseph Stilwell, Commander in Chief US China-Burma-India (CBI) Theater of Operations, Chief of Staff to Generalissimo Chiang Kai-Shek, Commander in Chief Northern Area Combat Command (NCAC) and Deputy Commander in Chief South-East Asia Command (SEAC), arrives at Ledo to take personal charge of the northern Burma campaign.
CHINA: Twenty nine USAAF Fourteenth Air Force B-24 Liberators bomb the railroad yards at Chiengmai; the warehouse area along the west side of the yards suffers very heavy damage. Fourteen B-25 Mitchells, with fighter escort, attack Hwajung.
NEW GUINEA: On the Huon Peninsula in Northeast New Guinea, the Australian 20th Brigade, 9th Division, crosses the Malaweng River. At 1600 hours, the leading company of the 2/15th Battalion enters Hubika which is littered with dead Japanese soldiers. One wounded soldier says, "Japan soldier he go Wandokai" and shortly thereafter, Australian (A-20) Bostons bomb and strafe Wandokai.
Task Force BACKHANDER, the task force for operations on Cape Gloucester, New Britain Island, Bismarck Archipelago, under the command of Major General William H. Rupertus, USMC, conducts a final rehearsal for invasion of Cape Gloucester at Cape Sudest, Papua New Guinea.
In Northeast New Guinea, USAAF Fifth Air Force A-20 Havocs hit camps north of Finschhafen, B-25 Mitchells bomb and cannon Madang and P-40s hit Kaukenau.
EAST INDIES: USAAF Fifth Air Force B-24 Liberators bomb Amahai Airfield on Ceram Island, Netherlands East Indies.
BISMARCK ARCHIPELAGO: On New Britain Island, USAAF Fifth Air Force pre-invasion air strikes continue against Cape Gloucester as over 100 B-24 Liberators, B-25 Mitchells, and A-20 Havocs attack the area. P-39 Airacobras strafe targets along Borgen and Rein Bays, P-40s and A-20 Havocs hit Hoskins Airfield, and P-47 Thunderbolts claim 17 fighters shot down in the Arawe area. between 1200 and 1720 hours.
MARSHALL ISLANDS: Eight USAAF Seventh Air Force B-24 Liberators from the Ellice Islands escort four USN PB4Y-1 Liberators on a photo mission over Kwajalein Atoll. The B-24s bomb shipping and airfields and other facilities at Roi, Ennuebing, and Kwajalein Islands. In other raids, 12 A-24 Dauntlesses, along with five USMC SBD Dauntlesses and 15 USN F6F Hellcats hit shipping and airfields at Emidj Island and 16 P-39 Airacobras strafe fuel dumps, shipping, and antiaircraft guns at Mili Atoll.
PACIFIC: Glen Boren's diary: Our shore stay at Espirito Santo was suddenly interrupted with a sudden call to get back to the ship (two hours notice). We knew something was up, but not what. We got underway immediately.
USS Grayling sinks fourth Japanese ship since 18 December.
SOLOMON ISLANDS: The relief of the 3d Marine Division in the beachhead line on Bougainville Island begins.
Six USAAF Thirteenth Air Force B-25 Mitchells attack Monoitu Mission on Bougainville and during the night of 21/22 December, snoopers bomb various bivouac areas.
U.S.A.:
Escort carrier USS Tulagi commissioned.
Destroyer escort USS Ahrens launched.
Destroyer USS Meredith launched.
ATLANTIC OCEAN:
U-284 was scuttled about 601 nautical miles (1114 km) south-southwest of Rekjavik, Iceland, in position 55.04N, 30.23W, by her crew after suffering major damage from floating ice; her sister boat, U-629 rescued the entire crew and brought them back to base at Brest on 5 January 1944.