World War One Diary for Saturday, April 7, 1917:
Air War
Western Front: Second Lieutenant Ball returns (to 56 Squadron) after teaching pilots in England. Richthofen’s 5 Albatros DIIIs shoots down 2 of 6 Nieuport fighters (No 60 Squadron), latter lose again 4 of 6 on April 16.
Sea War
North Sea: 4 British CMBs (Coastal Motor Boats) raid on Zeebrugge (night April 7-8); CMB8 torpedoes and sinks German destroyer G88 on April 8.
Politics
Cuba and Panama declare war on Germany (4 German ships seized Havana).