Norwegian artillery Major Hans Holtermann and 250 volunteers start reactivating the old fort at Ingstadkleiva near Trondheim, which will become known as Hegra Fortress. The fort has mothballed artillery (four 10.5 cm and two 7.5 cm in half-turrets and 4 Krupp m/1887 field guns) and plenty of ammunition. A German Major requests the fort’s surrender but Holtermann refuses.
Luftwaffe chief Generalfeldmarschall Hermann Göring forms Luftflotte 5, under his second in command Generaloberst Erhard Milch in Hamburg, to coordinate an expanding role in Norway. Luftwaffe duties include air defenses, airlifts and offensive strikes against Norwegian defenders and the Royal Navy. Milch will move his headquarters to Oslo to be closer to the action.
At 9.42 AM, U-37 sinks British steamer SS Stancliffe (carrying 7200 tons of iron ore) with 1 torpedo 45 miles northeast of Shetland Islands (21 lives were lost). 16 crew make land in the lifeboat at Haroldswick, Unst Island.