World War One Diary for Thursday, July 26, 1917:

Air War

Flanders: Major air battle over Polygon Wood involving 94 British and German aircraft, repeated on July 27 when more than c.20 Albatros fighters lose 9 aircraft to 2 British after Allied trap (59 Royal Flying Corps single-fighters plus French) sprung over the wood. Haig congratulates Trenchard on July 28.

Sea War

Channel: Minelayer-cruiser HMS Ariadne (38 lost) sunk by UC-65 off Beachy Head. UC-61 beached on Cap Gris Nez and surrounded by Belgian cavalry; Royal Navy recover documents showing British minesweeping report code broken.

Black Sea: Russian motorboat approaches Bosphorus, comes under German and Turk coastal gunfire, drops bottles with revolutionary anti-German proclamation to Turks (night July 26-27).

Home Fronts

Britain: Labour Party pledges one million new houses after the war.