British mine-laying submarine HMS Seal, running on the surface for speed in the Kattegat, is bombed by a Heinkel He115 at 2:30 AM. Seal dives to 30m & lays 50 mines from 9 to 9:45 AM but German anti-submarine trawlers begin searching the area. Seal zigzags to avoid detection until 6.30 PM when she hits a mine & settles on the bottom, stuck in mud overnight & running out of air.
Allies mass 30,000 troops (French Foreign Legion & Chasseurs Alpins [mountain infantry], Polish troops, British 24th Brigade & Norwegians) around Narvik, still hoping to retake the town & disrupt iron ore traffic from Sweden.. French move overland to secure Bjerkvik, on the shore opposite Narvik, but are held at Labergdal Pass.
General Feuerstein’s 2nd Gebirgsjäger (mountain) Division starts marching 350 miles North from Trondheim to relieve Dietl’s 139th Gebirgsjäger Regiment isolated in Narvik. Allies deploy 300-500 troops each at Mosjöen, Mo & Bodö to stop them.
Polish destroyer Grom and British destroyer HMS Faulknor are patrolling off Narvik bombarding German positions when Grom is struck on her torpedo tubes by a German bomb at 8.28 AM and sinks (58 lives lost). British cruisers HMS Enterprise & Aurora and destroyers HMS Faulknor & Bedouin rescue survivors, starting at 8.35. The Polish survivors are embarked on a hospital ship for the passage back to England, departing Harstad on April 10 for the Clyde.