Then Mr Davies was back in Australia on R&R with no sense of closure about a month after Operation Ivanhoe and the Battle of Nui Le in 1971.

The war came to an end and he felt like the battle "just faded into nothing".

Fifty years later, Mr Davies watched a virtual commemorative service on Monday, September 20 from his home in Pembrooke on the NSW Mid-North Coast.

The ABC, in association with the federal government's Department of Veterans' Affairs, provided a virtual commemorative service to mark the 50th anniversary of Operation Ivanhoe and the Battle of Nui Le.

The anniversary recognised the last offensive operation that Australians were involved in during the Vietnam War, including the last Australians to be killed in battle in Vietnam.

Mr Davies said he was pleased the campaign and battle were recognised, as at the time, the war was ending and the Australian troops were coming home.

Operation Ivanhoe, a search-and-destroy sweep of the area south of the Courtenay rubber plantation, involved infantry, armoured personnel carriers, artillery and engineers, along with air support.

There were no tanks to provide support. They had left South Vietnam to return to Australia less than a week before.

The Battle of Nui Le took place on September 21, 1971 as part of Operation Ivanhoe.

Mr Davies was a forward observer signaller with Delta Company 4RAR.

"We had to assault the bunker systems twice and it just seemed to go on for ever and ever," he said.

"We were heavily outnumbered and we retreated from one bunker system into another bunker system and were surrounded with the enemy even in the trees.

'When we were surrounded the whole company was confined to an area roughly the size of a football field."

Mr Davies paid tribute to his fellow members of the Delta Company forward observer party of Bombardier Russell Pullen, Gunner Ken Hayes (Zoomer) and Gunner Billy Drinkwater.

Mr Davies wants also people to know the size of the offensive operation.

"People thought that with the troops coming home it was quiet and there wasn't much happening," he said.

"But in fact, there was a lot more happening, because the North Vietnamese army came down in force as Australia was leaving and we didn't have the back-up or support."

Operation Ivanhoe ended on October 2, 1971. Six Australians died with 29 Australians and one New Zealander wounded.

About 60,000 Australians served in the Vietnam War including more than 15,300 national servicemen.

Mr Davies was among the national servicemen. He was 21 when he served in Vietnam for seven months during the war in 1971.

Mr Davies went on to found the Hastings Manning Macleay Vietnam Veterans' Association, and in the 2006 Australia Day Honours List, was awarded an OAM for service to the welfare of Vietnam veterans and their families, particularly in the Mid-North Coast.