During a period of less than a month, some 15,000 New Zealanders took part in the Battle of the Somme. More than 2000 died and another 6000 were injured.
Thousands have no known graves and their names are recorded on memorials to those whose bodies were never recovered.
The dawn service will begin with officials being led in by members of the New Zealand Defence Force's Maori Cultural Group. At its conclusion, participants will return to Longueval for a French-focused ceremony.
Hundreds of New Zealanders are expected at the ceremonies. The largest attendance is likely to be at the national commemorative service at the Caterpillar Valley Cemetery, starting at 9pm NZT.
Prince Charles and Defence Minister Gerry Brownlee will be among the dignitaries at the service, which will begin with a welcome by the Maori group.
Both will make addresses before singer Rebecca Nelson performs a song titled
Poppies and Pohutukawa
.
Youth readers representing France, Germany and New Zealand will then address the ceremony.
The final service will be a sunset ceremony back at the New Zealand Battlefield Memorial starting at 5am tomorrow NZT.
The centrepiece will be the performance of a musical item called
A Day in Battle
.
The event will conclude with a waiata and karakia.
You can follow live coverage of the commemorations at nzherald.co.nz and on Newstalk ZB from late afternoon today.