Overnight, Iraqis withdraw from the plateau overlooking RAF Habbaniya having suffered 1000 casualties from RAF attacks. They abandon 6 Czech 3.7 inch howitzers, 1 field gun, 1 Italian tank, 10 Crossley armoured cars, 79 trucks, 3 anti-aircraft guns, 56 machineguns, 340 rifles and 500,000 rounds of ammunition. They are pursued by King's Own Royal Regiment which leaves RAF Habbaniya in armoured cars (carrying 2 WWI-era 4.5 inch howitzers, previously used as ornaments at the entrance to the officers' mess). KORR routs the retreating Iraqi troops at the village of Sinn El Dhibban on the road back to Baghdad (433 Iraqis taken prisoner). British casualties are 7 killed and 14 wounded. 21st Infantry Brigade, 10th Indian Infantry Division, disembarks at Basra to reinforce the British presence in Iraq.
In Paris, senior German diplomat Otto Abetz and French Foreign Minister Admiral Darlan negotiate a preliminary agreement to send Vichy French war materiel in Syria to the Iraqis (in return, French “occupation costs" are reduced from 20 million to 15 million Reichsmarks a day). Although later rejected by the French government and never ratified, the Paris Protocols also allow Germany use of airbases in Syria to transport aircraft to Iraq. Luftwaffe Colonel Werner Junck is ordered to establish Fliegerführer Irak with 12 Messerschmitt Bf110 fighters and 12 Heinkel He111 bombers.
Allied commander on Crete, General Freyberg, receives accurate intelligence (Ultra intercepts of poorly-coded Luftwaffe signals) on German plans for an airborne invasion of Crete by 2 divisions on May 17. Freyberg does not believe a parachute attack is likely and continues to focus on the threat of amphibious landings with tanks.
U-103 and U-105 sink 3 more British freighters off Sierra Leone (12 killed, 100 survivors). U-103 rights a swamped lifeboat to accommodate more survivors from one steamer. 500 miles West of Ireland, U-97 sinks British ocean boarding vessel HMS Camito and Italian tanker SS Sangro which she is escorting to Britain (28 killed, survivors picked up by corvette HMS Orchis). Off the coast of Italy, British submarines HMS Taku and HMS Truant sink Italian steamers Cagliari and Bengasi.