New Zealand's darkest day is being remembered on the battlefield of Belgium and here at home.

It's 100 years since the deadliest battle of World War One's Passchendaele campaign.

846 of our men died on October 12 1917 more than any day before or after.

More than 100 died later from their injuries, following the bloody, muddy disaster of an attack.

Ceremonies will be held today at Auckland War Memorial Museum’s Cenotaph, Wellington's Pukeahu Park and Waiouru's National Army Museum.

A sunset ceremony is underway in Belgium, Dave Dobbyn will be among those taking part.

Dobbyn spoke with Mike Hosking about what the ceremony means to him.

LISTEN ABOVE AS DAVE DOBBYN SPEAKS WITH MIKE HOSKING