Germany: 7 Handley Page bombers (1 lost) of No 216 Squadron RAF cause two-day plant closure at Oppau chemical works, Mannheim (direct hit on gas main). Rail workshops and locomotives hit at Karthaus. 2 SVA-5s of Italian 87th Squadriglia photograph Zeppelin works at Friedrichshafen (440-mile round trip). 13 F.E.2s of No 100 Squadron dislocate rail traffic at Saarbruecken (night May 21-22).
Western Front: Udet appointed Commander Jasta 4.
Britain: Rumpler CVII (Drechsel and Foell) flies daring 375-mile high-altitude undetected photo-reconnaissance sortie over London, returns safely to Tournai base.
Ukraine: Peasant revolts against Germans and Haydamak allies. Sovnarkom starts peace talks with Hetman Skoropadski on May 23.
Armenia: Turk 36th and 9th Divisions throw back Nazarbekov’s c.9,000 Armenians from Amamll Station until May 22; Antranik’s 2,000 Armenians make rearguard stand near Jelal-oglu from May 22-23.