After dropping 65 million leaflets, Bomber Command suspends 'nickelling' operations over Germany.

The aerial photographs of MacPhail's mission over the Soviet oilfields and the accompanying intelligence evaluations arrive on the desks of the British and French general staffs. The Allied generals decide to concentrate on the refineries and oil tanks. The French Armee de la Air will raid Batum and the RAF will destroy the installations in Baku and Grozny. The staffs calculate that it will be possible to destroy a third of the targets in the first six days. The plans call for 9 bomber squadrons to level 122 refineries within a 10 to 45 days period. Two French squadrons of Farman 221s, 4 French squadrons of Glenn Martins and 3 British squadrons of Wellingtons were to be used the French flying from Cizre in Turkey and the RAF from Mosul in Iraq. With extra fuel the Allied fleet was expected to carry 70 tonnes of bombs per mission. The RAF anticipated a 20% loss rate, the French expected no losses. The general staffs believed that this would lead "to a total collapse of the USSR's war capacity", and even "decide the entire course of the war."

NORTH SEA: U-1 goes missing. Probably lost by a mine in the mine barrage Field No. 7. in the North Sea. 24 dead (all hands lost). (Gary Kao)

NORWAY: Operation Wilfred, the British mining of Norwegian waters, begins.

GERMANY: Kiel: RAF photo-reconnaissance reveals heavy naval activity at German ports in the area, believed to be in preparation for invasions of Norway and Denmark.

Operation Wesserübung: At midnight the Scharnhorst , accompanied by the Gneisenau, leaves Wilhelmshaven as the cover force of "Group I" for the invasion of Norway. (Navy News)

U.S.A.: A USAAC B-17 Flying Fortress is flown from Mitchell Field, Hempstead, Long Island, New York to Langley Field, Hampton, Virginia, by a pilot in a hooded cockpit using instruments. A co-pilot, navigator and four other crewmen were also aboard but they are not under a hood.

The maiden flight of the first production Curtiss (Model 81-A) P-40, USAAC s/n 39-156, takes place at Buffalo, New York. Deliveries of the 524 P-40s to the USAAC begin in June.