World War I: The First Battle of Passchendaele takes place resulting in the largest single-day loss of life in New Zealand history.

The First Battle of Passchendaele took place on 12 October 1917 during the First World War, in the Ypres Salient in Belgium on the Western Front. The attack was part of the Third Battle of Ypres and was fought west of Passchendaele village. The British had planned to capture the ridges south and east of the city of Ypres as part of a strategy decided by the Allies at conferences in November 1916 and May 1917. Passchendaele lay on the last ridge east of Ypres, 5 mi (8.0 km) from the railway junction at Roulers, which was an important part of the supply system of the German 4th Army.