Caribbean. At 1.15 PM 100 miles South of Santa Domingo, Dominican Republic, U-502 sinks neutral Brazilian SS Gonçalves Dias by mistake (6 dead, 39 survivors). At 4.40 PM 60 miles Northwest of Grand Cayman Island, U-103 sinks Dutch MV Hector (2 killed, 29 survivors picked up by American tanker FQ Barstow).
In Libya, General Neil Ritchie prepares with typical British thoroughness for an offensive against Rommel, finalizing all the details for a massive attack in June. In addition to 850 tanks, he has amassed huge stockpiles of supplies and munitions at Tobruk and created supply dumps in the desert. Just in case Rommel should attack first, British defenses on the Gazala-Bir Hacheim line consist of a series of dug-in infantry “boxes” (well-provisioned trench systems equipped with artillery, anti-tank guns and anti-aircraft guns) interspersed with large, densely-sown minefields. Most of Ritchie’s troops are concentrated near the coast, but further inland the “boxes” are too far apart to provide mutual support. Most of the British tanks (1st and 7th Armoured Divisions) wait 20 miles behind this line as a mobile reserve.
Battle of Kharkov. Germans quickly begin reducing the Soviet Armies encircled in the Izium pocket, using artillery, tanks and Luftwaffe bombing.
Japanese submarine I-21 launches its floatplane to reconnoiter Auckland, New Zealand. In a case of mistaken identity, New Zealanders turn on the landing lights at Auckland airport. I-9 launches its floatplane to reconnoiter Kiska Island and Amchitka Island (part of USA at the western end of the Aleutian Islands).
20 miles Northeast of Formosa (Taiwan), US submarine USS Pompano sinks Japanese fishing vessel Kotoku Maru with the deck gun.
Overnight, Luftwaffe bombers attack the Royal Navy seaplane training center at Poole, Dorset, on the South coast of England.