21 April 1944

UNITED KINGDOM: Corvette HMCS Mayflower completed work ups and departed for Greenock to join Western Approaches Command for invasion duties. As was the case before Operation TORCH, the concentration of naval power before Operation NEPTUNE required adjustments in convoy scheduling and escort arrangements. The average size of the ONS convoys for 1944 was 38 ships. In the period between Apr and Sep 44, the average ONS convoy size was 92 ships, with seven that numbered over 100 ships. This included the 'monster' convoy ON-249 of 153 merchant ships. Only one ship was lost to enemy action during this period.

HMCS Hespeler departed Londonderry, to join the escort for the 111-ship Liverpool to New York City Convoy ONS-233. The convoy arrived safely in New York on 09 May 44.

Destroyer HMS Hogue launched.

Frigate HMS Awe commissioned.

236 Ninth Air Force B-26 Marauders and 34 A-20s attack gun positions, coastal defences and V-weapons sites at Etaples, at Berck-sur-Mer, near Doullens, and in the Saint-Omer, Abbeville, and Amiens area; 4 B-26s are lost.

BELGIUM: ; 175+ Ninth Air Force P-47 Thunderbolts dive-bomb marshalling yards and concentrations at Montignies-sur-Sambre, Hasselt, Namur, and Haine-Saint-Pierre (France).

U-875 commissioned.

U-2324 laid down.

Twelfth Air Force A-20s blast an ammunition dump while P-47s attack train, rail lines, and motor transport behind enemy lines; other P-47s, along with P-40s and A-36 Apaches, attack railway lines and trains between Rome and Terni, between Rome and Tivoli, and between Orte and Attigliano; hit a motor transport concentration northeast of Rome; and attack several bivouac areas and gun positions in the battle areas.

ROMANIA: 100+ Fifteenth Air Force B-24s bomb marshalling yards at Bucharest; all 17 bomb groups dispatched are recalled due to bad weather but 7 groups fail to receive the recall signal; 150+ P-38s and P-51s are dispatched as escort; 40+ rendezvous with the B-24s and battle some 30 enemy fighters that attack the bomber force; the other fighters, failing to meet the bombers, engage about 40 enemy fighters; the bombers and fighters claim 35 aerial combat victories; 10 US aircraft are shot down.

U.S.S.R.: Black Sea Fleet: (Sergey Anisimov)(69)Submarine loss."L-6" - by surface ships, North to Constanta.

German Colonel-General (Generaloberst) Ferdinand Schorner begs Hitler to evacuate the 17th German-Romanian Army from Sevastopol. Once again, Hitler ignores a top military commander. He orders "Fortress Sevastopol" to hold out for eight weeks to discourage Turkey from joining the Allies. Hitler doesn't know that the Turks have already decided to remain neutral.

BURMA: Lt. Carter Harman of the 1st Air Commando made the first helicopter combat rescue in military history flying a Sikorsky YR-4, when he made 4 separate flights some ten miles into Japanese held territory to take out a light plane pilot who had made an emergency landing along with three wounded British soldiers. The underpowered aircraft would only take one passenger at a time. (Chuck Baisden)

The Tenth Air Force dispatches 12 B-25s and 14 P-51 Mustangs to attack Indaw and Mawlu, causing several fires in supply dumps and in the general target areas; 12 B-25s bomb the camp and supply area at Kamaing. 8 B-24s bomb storage and fuel dumps at Lashio and bomb Namtu; 13 B-24s bomb Maymyo while 5 B-25s knock out 3 bridges in the Tangon area; and 4 P-51s knock out a bridge at Shweli.
Twelve Fourteenth Air Force P-40s fly armed reconnaissance over roads, strafing bridges, buildings, steamrollers, trucks, and troops in areas around Takaw, Bhamo, Loiwing, Kutkai, Hsenwi, and Lashio; at least 3 steamrollers and 7 trucks are destroyed.

Air Commando Combat Mission No. 47 2:55 Flight Time. Bombed Japanese troops at Mawlu for the 4th day in a row. (Chuck Baisden)

NEW GUINEA: The US TF 58 attacks Japanese airbases at Sawar, Sarmi, Wakde Island and Hollandia to pave the way for tomorrow's landings.

Amplifying the above, Task Forces 58 and 78 begin a preinvasion aerial bombardment. Fighters from Task Group 58.1 attack Wakde Island and Sarmi at dawn and then surface vessels and aircraft of the two Task Forces attack Aitape, Hollandia, airfields in the Hollandia area and Wakde Islands. Many Japanese aircraft are strafed on the ground but the fuel has been removed from them and few burn.

21 Fifth Air Force B-24s bomb airstrips on Noemfoor Island, Schouten Islands while about 320 B-24s, B-25s, and A-20s hit numerous targets in the Tadji, Wewak, and Madang areas.

BISMARCK ARCHIPELAGO: In spite of heavy weather in the Bismarck Archipelago, 24 Thirteenth Air Force B-25s bomb the Matupi supply area on New Britain Island.

MARSHALL ISLANDS: Seventh Air Force B-25s based on Abemama Island use Majuro Atoll as a shuttle base to bomb Jaluit and Maloelap Atolls.

CAROLINE ISLANDS: Seventh Air Force B-24s from Kwajalein Atoll hit Wotje Atoll while B-24s from Eniwetok Atoll, staging through Kwajalein, bomb Truk Atoll. B-25s from Engebi Island, Eniwetok Atoll, bomb Ponape Island.

SOLOMON ISLANDS: 11 Thirteenth Air Force P-39Airacobras, closed out of Rabaul, New Britain Island in the Bismarck Archipelago, bomb Tinputs Harbor on Bougainville Island.

Destroyer escort USS Conklin commissioned.

Submarine USS Croaker commissioned.

Minesweeper USS Mainstay commissioned.

Escort carrier USS Thetis Bay commissioned.

ATLANTIC OCEAN: 2 men died when they were stranded topside during an emergency dive by U-860 to avoid an incoming aircraft. [Matrosengefreiter Alfons Robalewsky, Bootsmaat Rudolf Versic].