It had seemed a lifetime since he'd begun his battle to have his service history acknowledged by officials and when it came on April 1, in a letter penned by Major-General Fergus McLachlan of the Australian Army, the relief was life-changing.

"I felt a sense of pride. I felt things I'd never felt before and I held my head high," says Tate. "It was the first time I'd ever received a hand up from the army."

In the letter, McLachlan encouraged Tate to take pride in the sacrifice he'd made for his country. His eight months in Vietnam ended after he was shot in the hip by the Viet Cong.

He spent two years in a Brisbane hospital recovering from the machine gun wounds, of which the first 12 months was spent in a head-to-toe cast.

"I want to apologise on behalf of the army for maladministration of your records over a number of years, starting during your service in Vietnam, but most regrettably extending long after your return home," McLachlan wrote in the letter. "This maladministration has resulted in you being unfairly vilified by sections of the veteran community who have used administrative gaps in your records to question your service history."

Tate, after sending hundreds of letters to authorities and writing two books, The War Within, and Anzacs Betrayed, became the victim of an eight-year cyber bullying campaign.

In a cycle of hate, the bullies - all veterans - swiped at Tate with accusations so foul that they are not worth repeating, and Tate aggressively and repeatedly defended himself, often to his own discredit.

"My responses I admit were aggressive," says Tate. "But I was at the point of despair and almost suicidal. To be called a liar, a fraud, a wannabe is terrible. I retaliated."

The cyber bullying would have continued except that the national chairman of the Royal Australian Regiment Association, former Major Michael Von Berg, decided enough was enough. Von Berg contacted Tate late last year and listened to his story.

After his own investigation, he provided Tate with two important documents. A statutory declaration of soldier John Walker, who was wounded alongside him in 9RAR's Operation "Hat Ditch" in the Long Khan Province on July 19, 1968. Also, a letter from Tate's former company commander Laurie Lewis outlining Tate's actions in battle.

Von Berg said the cyber vitriol questioned Tate's integrity and the nature of his wounding, including that Tate had been running away from the enemy when he was shot.

Walker set the record straight: "Don Tate walked passed me about five metres and he got hit bad in the hip," Walker wrote. "It spun him around two or three times before he hit the ground and I know the bullet came from the direction of the enemy."

Von Berg, who sits on the Prime Ministerial Advisory Council on Veterans Mental Health, has now pleaded for the attacks against Tate to end.

"Once these puerile attacks are in cyberspace everyone can see them and I just found it so deplorable," Von Berg says. "So I checked out [Tate's] story and the nature of his war injuries is indisputable. What they were saying about him was unacceptable. Unless they were physically there those people wouldn't know a damn thing. Who are they to question another soldier's integrity? For Don and his family this has been hell."

Tate's record on the nominal roll has been recently updated to show that he served in four units - not two.

It took him 28 years to gain recognition that he had served under the 9th Battalion. Film footage he had taken during his service and his hospital records helped in that regard.

However, the existence of the 2nd D&E Platoon has been much harder to prove. Instead the nominal roll says that he served under Headquarters Company.

The ad hoc platoon was created without the required paperwork and without the permission of the Australian cabinet. The unit of 39 soldiers was together for six weeks. They were disbanded following an incident which Tate says has been described by the Australian Federal Police as being at the "low end of the atrocity scale". The allegations involved the disposal of enemy bodies which he claimed were dragged into a crater and blown up in a propaganda move to warn the Viet Cong. An Australian Federal Police investigation into the allegations resulted in no charges being laid. Tate alleged the unit's records were corrupted after the incident.

In 2008, the government acknowledged the existence of the 2nd D&E Platoon, but the Australian War Memorial still refuses to recognise it as it was not formally recorded on the Order of Battle.

Tate knows he has lost the battle with bureaucracy, but is relieved to have been validated by a serving major-general.

"For me that apology is the most significant thing in my life. It has validated me in every respect," he says. "I won't win the formal acknowledgment of the 2nd D&E, but at least now people know that it existed."

Last year Tate received a $50,000 compensation payout from the Defence Force Response Taskforce.

"This has taken 45 years of my life. The integrity of a man's service records is sacrosanct. You've put your life on the line, you've been shot, you've sacrificed," he says. "To find that your name is missing from the battalion records is absolutely devastating. I cannot tell you how much that hurt me. But I'm glad now that my family finally knows the truth. That's what is important."