Lance Corporal Jared MacKinney will never see his unborn son.
The 28-year-old soldier died in a firefight in Afghanistan on Tuesday, the fourth Australian death in a fortnight.
Lance Corporal MacKinney's wife Beckie, pregnant with the couple's second child, said he had been looking forward to meeting "his little man".
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In a statement issued via Defence, Ms MacKinney paid tribute to her husband.
"Jared was a very loving Dad, a doting father, and nothing meant more to him than family," she said.
Ms MacKinney said the couple's first child, three-year-old Annabell, was his little princess.
Lance Corporal MacKinney is the 21st Australian soldier to die in Afghanistan - the 10th this year. He was shot dead during a three-hour battle with insurgents.
He died the same day that two fellow members of the Brisbane-based 6th Battalion began their final journey home.
Last Friday, Privates Grant Kirby, 35, and Tomas Dale, 21, died in the blast of an improvised explosive device.
All three were members of the Mentoring Task Force, responsible for training the Afghan National Army (ANA) 4th Brigade.
Defence head Air Chief Marshal Angus Houston on Wednesday said Lance Corporal MacKinney was part of a foot patrol of Australian and ANA troops who came under fire from a significant insurgent force in the Deh Rawood green zone, west of the Australian base at Tarin Kowt.
His colleagues moved him out of danger and rendered immediate first aid but could not save him.
Patrol members remained engaged with insurgents for almost three hours, calling in an Apache attack helicopter that strafed enemy positions with its 30mm cannon. A precision-guided weapon was also deployed.
The location was previously the operational area of Dutch troops.
Early last month, as the Dutch began their drawdown, Australian troops made their first patrol into the area.
Like much of southern Afghanistan, the region features arid desert with a lush, heavily cultivated and populated river valley green zone.
The increasing Australian toll has come with the Afghanistan summer fighting season, marked this year by escalating fighting and an increase in international casualties - 458 so far, compared with 520 for all 2009.
Despite the rise in casualties, Air Chief Marshal Houston said he believed the tide was turning as the US troop surge peaked.
"We are going into areas where the coalition and the ANA have not been before," he said.
"The Taliban are fighting back and we are seeing a lot more violence, a lot more activity."
Defence Minister John Faulkner said Australia had lost a fine and dedicated soldier.
"He was also a much-loved young man whose death is going to leave a terrible, terrible gap in the lives of those around him," he said.
Both Prime Minister Julia Gillard and Opposition Leader Tony Abbott expressed their condolences while backing the Afghanistan mission.
Ms Gillard said it was always anticipated this would be a dangerous time.
"It goes without saying this is dangerous and difficult work ... but it's also vital work," she said.
Mr Abbott said the mission was vital for Australian and global security - now was not the time to waver.
"Obviously, our soldiers are paying a high price to protect Australians and others from the threat of terrorism, but this is a very important struggle and it cannot be abandoned," he said.
In the statement from Defence, Lance Corporal MacKinney's mother Jane remembered him as a keen sportsman who loved hockey and rugby league.
He was dedicated and realistic about the risks of his work, she said.
"He was very competitive with himself and set very high personal standards," she said.
