"When it gets a bit harder out on the road, think of those before us, on the battlefields in Afghanistan, Iraq, Gallipoli, they did it tough - we don't," one of the walkers said.

Silent tears fell during a ceremony at Katherine's cenotaph this morning, when a white and a green balloon were released to remember a fallen digger.

Today would have marked Private Nathaniel Gallagher's 25th birthday.

Private Gallagher, from from Wee Waa in NSW, enlisted in the army in 2007 and he was on his second deployment to Afghanistan when he was killed in a helicopter crash in August 2012.

The group of walkers - around former Katherine man Ray Palmer - embarked on their journey from Mataranka to Darwin's Robertson Barracks on Saturday morning.

"We're going to walk 400km - 10km for every boy we have lost in Afghanistan," Mr Palmer said.

The group is raising money for the families of fallen soldiers and to diggers who are suffering from Post Traumatic Stress Disorder after coming back from conflict and war zones.

The walkers are expected to arrive at Robertson Barracks on April 22.

In 2010 Mr Palmer's son Scott was tragically killed in a helicopter crash in Afghanistan.

In November last year Mr Palmer, his wife Pam and a group of family members of other fallen diggers, visited the Tarin Kowt region in Afghanistan.

"We were invited to see where our son had served," Mr Palmer said.

"We were very humbled and moved - and when we showed one of the pilots on a map where it (the helicopter crash) had happened, he took us there and we flew over the area.

"The boys go over there (to war) and you expect them to walk off the plane when they come home - our Scotty came home in a casket.

"It is hard to deal with it. Very hard."

Wiping away tears while talking about his fallen son, Mr Palmer said the family had drawn strength and "some form of closure" from the opportunity to see the place where Scott lost his life. 

"Serving in the Army and being a Commando had been his long held dream. True to his nature, he lived his dream with distinction.   

"We lovingly remember the man whom Scott was: a devoted son and brother to his family; a best friend to his father and his brother, Adam; always loyal to his mates.

"To us all Scott was a larrikin who made us laugh, he had mischief in his smile, love in his heart, and was completely generous regardless of circumstance."

Yesterday, the group of walkers was joined by RAAF Tindal Commanding Officer 17SQN Wing Commander Mark Larter, who served in Afghanistan in 2012 - the year Private Scott Palmer was killed.

"It was fantastic that Mark joined us," Mr Palmer said.

"Mark's been over there (in Afghanistan) - he understands.

"He's very compassionate."

A fundraiser dinner will be held from 7pm at Emerald Springs Roadhouse on Wednesday night.