USA: Liberty Loan Act $7 billions ($3 billions for Allies).
Russia: Ukraine demands autonomy.
France: 155mm GPF gun first test fired (at Paris).
Salonika – Battle of Lake Doiran (until April 25): British 22nd and 26th Divisions attack on 2 1/2-mile front at 2145 hours but, under 147 Bulgar guns (including German 5.9-inch naval gun battery) and 33 searchlights, never penetrate beyond first line of concrete defences on steep round hills. British losses 3,163; Bulgar and German 835+ (22 PoWs) soldiers, including in 7 counter-attacks.
Mesopotamia: General Cobbe occupies Samarra (60 miles north of Baghdad, railway station occupied on April 23), takes 340 sick and wounded Turkish soldiers. Marshall drives 2,000 Turks east over Adhaim taking 160 PoWs but heat halts operations.
Western Front: 5 of Richthofen’s fighters survive attacks by 20 Royal Flying Corps fighters. First German Kampfstaffel or ‘Battle Flight’ special ground attack with MGs and hand grenades in support of infantry attack.