Day 588 April 10, 1941

Overnight, RAF bombs Berlin destroying the Opera House (Deutsche Staatsoper built in 1743). It will be restored by 1943 and then bombed out again in February 1945.

At 3.45 AM, U-107 sinks British tanker Duffield carrying 11,700 tons of fuel oil to Gibraltar (25 crew lost, 28 survivors make land at Hierro Island, Canary Islands). At 7.55 PM 500 miles Southwest of Iceland, U-52 sinks Dutch SS Saleier carrying coals from Newcastle to Port Said, Egypt. All 63 crew abandon ship in 3 lifeboats and are picked up next day by American destroyer USS Niblack (which is en route to Reykjavik, Iceland, and not a convoy escort). USS Niblack makes a false sonar contact and drops 3 depth charges (first "shot fired in anger" against Germany).

Kriegsmarine orders the construction of 60 U-boats.

In Yugoslavia, German troops capture the Croatian capital of Zagreb. Further South, 9th Panzer Division and Leibstandarte SS Adolf Hitler Regiment move through the Monastir gap and capture the town of Florina 8 miles across the Greek border.

East Africa. Although most of Italian Somaliland, Ethiopia and Eritrea is in British hands, pockets of Italian resistance still hold out (Assab in Eritrea; in Ethiopia, Amba Alagi in the North, Jimma in the South and Gondar in the West). In Ethiopia, Nigerian troops (11th African Division) moving Southwest down the road from Addis Ababa towards the Italian stronghold at Jimma reach the Omo River crossing at Abalti, to find the bridge blown and Italian troops dug in on the far side. In Eritrea, 5th Indian Division moves back from Massawa to Amara to pursue the Italians South to Amba Alagi in Ethiopia. Italians anticipate the arrival of British forces at Assab and seek to deny them use of the port facilities, scuttling 7 freighters in the harbour.

Rommel orders probing attacks on the defenses at Tobruk but they are turned back by Australian in fantry and British artillery. General von Prittwitz, commander of 15th Panzer Division (which will soon come from Italy to join the Afrika Korps), has been flown to Libya with an advanced party of 3500 troops as reinforcements. He is killed when his reconnaissance group of armoured cars is hit by anti-tank fire on the Tobruk perimeter.

Overnight, RAF again bombs German battlecruisers at dock in Brest, France. Gneisenau is badly damaged by 4 bombs and will be under repair at Brest until December. Luftwaffe bombs Birmingham, England, for a second night. 206 aircraft drop 246 tons high explosive bombs and 1,183 incendiary canisters.