Locals and tourists alike made their way to the War Memorial Centre just after 5am for the start of the Whanganui ANZAC dawn parade.
Thousands of people stood in the thick fog, in silence, as they gathered to remember those that had fallen.
Reverend Rosemary Anderson said Anzac Day in recent years had covered various parts of World War I as their 100-year anniversaries arrived.
But this year would mark a century since "the blackest day in our military history".
An assault launched by New Zealand forces at Passchendaele on October 12, 1917 resulted in "a catastrophic massacre".
She said it was an event often overshadowed by Gallipoli but ranked as "the very worst on New Zealand's path toward nationhood".