Battle of the Atlantic

• The Polish destroyer Grom is sunk off Narvik by German bombing with the loss of 58 crewmen. Her survivors are rescued by the British light cruiser Enterprise.
• The British submarine Seal lays mines in the Kattegat, then is badly damaged by a mine herself. She is captured and towed by the German trawler Franken to Frederikshavn. Her crew of 54 are taken prisoner. The ship will be repaired and enter German service in November. 4 ships will be lost in the minefield laid by the Seal. The first ship lost is the Swedish fishing boat Aimy (200t) on this same day.
• The British submarine Severn intercepts the Swedish steamer Monark (1786t) off Stavanger. She had been seized by German force on April 9. After removing the prize crew, which were from the German light cruiser Konigsberg, the Severn torpedoes and sinks the Monark.
• The British tanker San Tiburcio (5995t) sinks 4 miles from Tarbett Ness in Moray Firth on a mine laid by U-9 on 9 February. The crew is rescued by the British anti-submarine trawler Leicester City and the British destroyer Codrington.
• The Norwegian steamers Blaafjeld (1146t), Pan (1309t) and Sekstant (1626t) are sunk by German bombing near Namsos. The entire crews of the Blaafjeld and Sekstant are rescued. Also sunk by German bombing is the Norwegian steamer Aafjord (335t) at Breiviken.

Holland

In the Netherlands suspected Nazi saboteurs and their sympathizers are arrested.

Norway

British troops land at Mo, south of Narvik. The Polish destroyer Grom is bombed by 3 He-111s and sinks off Narvik. 59 of her 180 crew are lost.

Secret War

Papal Nuncio warns King Leopold of Belgium that a German attack is imminent.