"These boots are made for walkin' and that's just what they'll do. One of these days these boots are gonna walk all over you."

For a group of young Australian soldiers about to head to the Vietnam War, this 1966 Nancy Sinatra hit struck a chord.

It perfectly summed up the testosterone-filled bravado of the more than 100 men of D Company 6RAR and what they intended to do to the enemy when they met.

They adopted it as their theme song and a pair of digger's boots soon featured on the unit's logo.

Little did they know they would get to fulfil their wish just six months later in one of the most courageous victories in Australian military history, against overwhelming odds of about 20 to one, in a blood-soaked rubber plantation at Long Tan.

Paradoxically, since the battle, some in authority have "walked all over" the largely unrewarded heroes, in what retired Colonel Harry Smith calls a cover-up at the highest military and political echelons.

Remembrance services were held across Australia today for Vietnam Veterans Day.

The Battle of Long Tan lasted just four hours on August 18 in 1966, but for Colonel Smith, Delta (D) Company's commander, the torment of his memories and a fight against those who managed the gallantry honours system has continued to haunt him for the past 49 years.

Immediately after the battle in which 18 Australian soldiers and hundreds of the defeated enemy died, Colonel Smith recommended 20 of his men for gallantry awards.

The recommendations were largely ignored.

Four were rejected on the spot, including a Victoria Cross for Sergeant Major Jack Kirby.

Of the 16 nominations remaining, half were knocked back and some of the remainder were downgraded.

Harry Smith gives orders to the company the morning after the Battle of Long Tan. ( Supplied )

'He wasn't there and that is a rort'

Colonel Smith has written a book called Long Tan: The Start of a Lifelong Battle which is being launched today.

In it, he revealed his two immediate superior officers embellished the role they played in the battle to receive the highest gallantry awards at the expense of his men.

Colonel Smith said his commanding officer was nominated for a Distinguished Service Order — the second highest award behind a Victoria Cross — and a Vietnamese Medal.

He said the commanding officer claimed he moved out from Nui Dat and took over command and fought his battalion against an enemy regiment with success.

"He wasn't there and that is a rort," Colonel Smith said.

Colonel Smith also said the commander of the Australian Taskforce at Nui Dat received a Distinguished Service Order for his good service over time and personally directing the battle.

"For most of the time the battle was on, when the shit hit the fan, he went to his personal tent and didn't reappear until there was an argument about the helicopters," Colonel Smith said.

"It has been testified that is where he was, in his tent, probably pondering his career after he stuffed up in not passing on the intelligence about the enemy and he realised all hell was going to break loose on him."

Colonel Smith in Nui Dat, Vietnam. ( Supplied: Colonel Harry Smith )

Colonel Smith said the two men gave wrong accounts of their actions to the Australian commander who was not in Vietnam, but used their information for their citations for medals.

He only fully uncovered how and why his men did not receive proper recognition after 1996 when the 30-year Official Secrets Act expired and their version of events was revealed.

After three reviews since then, Colonel Smith had a significant win in 2011 when he and two of his officers had their decorations upgraded.

He said that embarrassed him and added he would not rest until the remaining 12 soldiers he wanted decorated almost half a century ago were recognised.

Colonel Smith feels the time is now right to speak up about his two former commanding officers.

"I've never, ever gone into the detail of what was in their citations but at 82 years of age I feel it's time for people to know exactly what was in their citations and that they were perjury," he said.

The ABC has contacted the Defence Department and a ministerial adviser of the Department of Veterans' Affairs for comment.

'Mates give mates awards'

Retired Major General John Cantwell, who was commander of Australian forces in the Middle East in 2010, and deputy chief of Army before that, agreed their actions were questionable.

He said there were "absolutely unforgivable failures of leadership and administration" when it came to medals for Delta Company 6RAR and some of the others who supported that battle.

"Any reasonable person who looks at what occurred in terms of the distribution of honours and awards after that battle would have to raise real doubts about who got what medal and for what reason," he said.

"It's pretty obvious that senior officers who weren't involved in the fight look after themselves and sprinkle them and their mates with high awards."

The quota system for rewarding gallantry that was in place for Australian troops in Vietnam in 1966 worked against D Company's heroism being fully acknowledged.

Cooks and postal staff working behind the lines received awards while those on the front line missed out.

Only one medal could be awarded for every 250 soldiers and one Mentioned in Despatches given out for every 150 soldiers during a six-month period irrespective of the amount of action they saw.

The soldiers Colonel Smith fought alongside in Long Tan. ( Supplied: Colonel Harry Smith )

Colonel Smith describes it as a "ration on gallantry" while Major General Cantwell believes many remarkable acts of courage at Long Tan went unrecognised.

"It's a really dark spot in my view on our military history," Major General Cantwell said.

"Thank heavens the honours and awards system has now changed and indeed many of those failings of character and leadership and administration that affected Harry and his team have been corrected.

"The fact that they had a quota in place seems to infer that there is some sort of finite number of bravery acts that are permitted in any one battle — that's madness.

"Not only was there some terrible loss of life but we saw a travesty of justice when it came to the awards and honours that should have gone to those brave soldiers, that didn't."

Major General Cantwell said D Company's amazing feat of arms against such a vastly bigger enemy force of up to 2,500 troops was a great success that could not be compared to any other action in Australian military history.

He said it probably prevented an attack on the poorly defended main Australian base at Nui Dat.

Fresh tribunal hearings offer hope

From next month, the Defence Honours and Awards Appeal Tribunal is due to start hearing Colonel Smith's claims to have the remaining 12 soldiers given the recognition he is adamant they deserve.

Colonel Smith said in recent years the tribunal had recommended awards back to World War II and Vietnam.

"I think the tribunal now understands that justice has to be done and you just can't keep on going on and on saying we can't go back in time," he said.

The efforts of the men Colonel Smith nominated may not have been recorded correctly by their senior officers, or the accounts may have been lost, he said.

"[The tribunal] claimed that you've got no evidence to say that they were recommended, only your testimony," he said.

"If they can't accept my testimony and my soldiers' and officers' testimony on oath — well there's something wrong with the system."

Colonel Smith prepares to receive a medal. ( Supplied: Colonel Harry Smith )

Colonel Smith urged the tribunal to think carefully in its deliberations to finally right the injustice.

"It'd be wonderful. It'd be like having a 50th birthday again," he said.

"I know that there are a lot of soldiers however that fought in other units, even in Afghanistan, who should have got awards and didn't.

"But Long Tan has been put up on a pedestal by the Australian public and the ex-service public and it needs to be put to rest and I hope that it is done before the 50th [anniversary]."

That Nancy Sinatra song still means a lot to Colonel Smith after all these years — it is the ringtone on his mobile phone.

"These boots are made for walkin' and that's just what they'll do. One of these days these boots are gonna walk all over you," he said.

"I didn't withdraw at Long Tan and I won't withdraw from the fight to have my men properly recognised."