Holding his wife, he began to cry.

"A song, sound, smell, anything can set you off," Mr Kearns said, as he stood in the rain among friends and dignitaries at a ceremony for Vietnam Veterans Day on Saturday.

He was one of dozens of veterans, partners, children and dignitaries who braved the weather to commemorate the day, at an event in front of the Vietnam War Memorial on Anzac Parade.

Governor-General Peter Cosgrove acknowledged that each year, the contingent wanes.

In his speech, Sir Cosgrove reminded the assembled military personnel it was their duty to carry out their duties "regardless of the weather, season or terrain".

"Please remember that," he joked as rain poured from above.

The Governor-General talked about the spirit of "service before self" which Vietnam veterans embodied, and crucial role they had played in establishing that spirit as an Australian value.

He noted that he and his fellow veterans were showing the affects of age and each year there were fewer of their Vietnam colleagues at events such as this memorial. He said it was important, now more than ever, that returned servicemen and women reached out to support each other.

It was a message echoed by almost all of the speakers at the memorial, including ACT Vietnam Veterans Federation president Ian Thompson, acknowledging the significant trauma veterans withstood and the affects, both mental and physical, that war had on those exposed to it.

"We must acknowledge the undeniable fact that our younger brothers and sisters continue to do it tough," Mr Thompson said.

"We must extend the hand of mateship further."

Mr Kearns and former RAAF pilot Mick Haxell recalled witnessing their mates face the difficulties of returning home after the Vietnam War.

"I can remember mates of mine that I served with, it seemed to come out in anger," Mr Haxell said.

"We knew it came from their time in the service. But there was no assistance or recognition."

Mr Kearns added that at the time, "to go and seek help was a sign of weakness, so they bottled it up."

However both men said support services had improved significantly and credited the work of the Veterans Support Centre in Page. Memorials such as Saturday's event were occasions to join old mates, enjoy the fellowship and camaraderie forged all those years ago and remember those that didn't come home, they said.

"Today is a great day," Mr Kearns said.

He particularly enjoyed sharing stories amongst friends which each year he said "get longer, stronger and bigger."

On Friday the Long Tan Cross was unveiled in its new home at the Australian War Memorial 52 years after the battle.