Germany: Ludendorff orders Aisne attack preparations by German Crown Prince.
Flanders: German offensive renewed but without decisive effect; Wytschaete and Meteren captured.
First Battle of Kemmel Ridge (until April 19): Belgians take 700 PoWs and 42 MGs northwest of Dixmude.
Somme: Heaνy German mustard gas attack on Villers-Bretonneux.
North Sea: Dover Patrol monitors Erebus and Terror shell Ostend.
North Atlantic: 4 Royal Navy drifters sink coastal submarine UΒ-82 in Northern Channel.
Adriatic: Italian submarine Η5 sunk in error by HM Submarine Η1.