Estimates show about 30 veterans who were at either Fire Support Bases Coral and Balmoral, now reside in Tasmania.
The 50th anniversary of the two key Vietnam War battles falls on Sunday.
Fire Support Bases Coral and Balmoral were a series of actions between May and June 1968.
The bases defended positions for artillery and mortars, which supported infantry patrols in the area.
A total of 26 Australians were killed during the fighting at FSB Coral and Balmoral. Estimates suggest that more than 300 North Vietnamese were killed in these actions, but exact figures will never be known.
The Battles at Coral and Balmoral resulted in more Australian casualties than any other series of engagements in Vietnam.
A national commemorative service to mark the 50th anniversary of the Battles at Fire Support Bases Coral and Balmoral will be held at the Australian Vietnam Forces National Memorial in Canberra on Sunday.