Anzac Day is a national day of remembrance in Australia and New Zealand, commemorated by both countries on 25 April every year to honour the members of the Australian and New Zealand Army Corps (ANZAC) who fought at Gallipoli in the Ottoman Empire during World War I. It now more broadly commemorates all those who died and served in military operations for their countries.^[1][2] Anzac Day is also observed in the Cook Islands, Niue, and Tonga. It is no longer observed as a national holiday in Samoa.

Anzac Day marks the anniversary of the first major military action fought by Australian and New Zealand forces during the First World War.^[3] The acronym ANZAC stands for Australian and New Zealand Army Corps, whose soldiers were known as Anzacs. Anzac Day remains one of the most important national occasions of both Australia and New Zealand,^[4] a rare instance of two sovereign countries not only sharing the same remembrance day, but making reference to both countries in its name. When war broke out in 1914, Australia and New Zealand had been dominions of the British Empire for thirteen and seven years respectively.