Australia remembers Battle of Fromelles

Sir Peter Cosgrove has marked 99 years since the bloodiest day in Australian military history claimed more than 5500 lives in the Battle of Fromelles during World War I.

The Governor-General was joined by about 200 people, including descendants of those who died in battle, at Melbourne's Shrine of Remembrance on Sunday.

Fromelles was the first major battle involving Australian troops in France in WWI. It was fought over July 19 and 20 in 1916 and resulted in 5533 Australians being killed, wounded, or taken prisoner.

"It was a bloodbath right from the start," said Graham Williams from the Friends of the 15th Brigade association.

He said it was tragic the battle went ahead even though Australia's commanding brigadier wanted to call off the attack because it involved crossing too much land to reach enemy territory.

Many wounded Australian and British soldiers were also left to die in No Man's Land after British generals refused to accept a German truce which would have allowed them to reclaim the wounded.

Mr Williams says it's important to remember the military disaster.

"By commemorating them you're not allowing them to be forgotten, and by not forgetting it you're less likely to be inclined to support other wars because you see the tragedy," he told AAP.