Western Front – ‘BLOODY APRIL‘: Richthofen’s ‘Flying Circus’ rules the skies. Only the exploits of Collishaw, Dallas, Little and the Sopwith Triplanes of RNAS ‘Black Flight’ hold promise the tide will eventually turn. Royal Flying Corps has 754 aircraft (41 squadrons) in France.
BEF establishment strength 1,893,874 men (including 139,353 Anzacs and 130,255 Canadians).
Somme: British Fourth Army capture Savy with Savy Wood 4 miles west of St Quentin. French President Poincare visits liberated area.
Aisne: French push back Germans to Vauxaillon northeast of Soissons.
Champagne: Germans shell Reims (25,000 shells in one week).
Atlantic: APRIL SHIPPING LOSSES (373 Allied ships) REACH RECORD MONTHLY TOTAL OF 545,200t (world-wide losses 873,754t). Now 120 German U-boats in service. In April British Aircraft join seaplanes on anti-U-boat patrols.
USA: 600,000t German merchant shipping (interned since 1914-1915) seized by US.
Mediterranean: In April Japanese 2nd Detached Squadron (Rear-Admiral K Sato), cruiser Akashi and 8 wartime-built destroyers arrive (c.April 17), based at Malta (made public by lord R Cecil on May 24). Cruiser Idzumo arrives with 4 more destroyers in August, 2 Royal Navy destroyers turned over in June.
Adriatic: Austrian U-30 lost by unknown cause in Otranto Straits (or following day).
Baltic: In April Bolsheviks claim 1,400 members aboard 22 ships.
France: Langevin tests his first quartz transmitter in laboratory tanks, it kills fish in its path.