The Group Captain and first serving woman to address an Anzac Day dawn service in Melbourne told the tens of thousands packed around the Shrine of Remembrance about courage on the field.

"My medals represent personal hardship, specific challenges and many victories. Medical battles with scalpels, antiseptics, blood and dressing," she said.

"They remind me of the emotion we faced living in the devastation in Aceh, its streets and rivers choked with the debris of thousands of bodies."

An estimated 35,000 attended Wednesday's service, which marks 100 years since the WWI battle of Villers-Bretonneux when Australian soldiers and their allies recaptured crucial territory from the Germans.

The numbers swelled by 10,000 from last year which organisers attributed to better weather and the ongoing commitment of Victorians to honouring service and sacrifice.

One former soldier at the service, Chris Walters, sees that day as more about his father and grandfather.

"I still never see today as respect to me. It's more I still think of my grandfather (who) served. My dad was in the RAAF for 20 years," he told AAP.

Mr Walters said the traditional minute's silence during the service carried mixed emotions.

"I've lost friends and I know people who are struggling with things like PTSD and those that have returned."

For years Vietnam veteran Sui Kamid wasn't recognised for his service, but this has now changed.

"We never got any recognition for years and years, 20-odd years or so. So it was pretty hard to take in the beginning," he said.

To reflect the changing face of Anzac Day, current veterans are due to lead the traditional Anzac march down St Kilda Road later on Wednesday.

"It is a decision ... that we would turn the march on its head and have the younger veterans matching at the front," Victorian RSL president Rob Webster told ABC TV.

Australian Associated Press