The annual ceremony at the public memorial on Kapooka Road had to be cancelled due to coronavirus pandemic restrictions.

Instead, the Army laid a wreath at the memorial on Thursday morning.

Wagga historian Sherry Morris, who has written a book about the incident, said the loss of so many young lives was a shock to both the army base and the city.

"It brought the reality of war back to Wagga and the war was almost over, which made it more tragic," she said.

On the afternoon of May 21, 1945 a group of Army trainee sappers and their instructors entered an underground dugout for a demonstration on how to prepare explosives.

Minutes after they arrived at 2.30pm, some or all of the 50 kilograms of explosives kept in the dugout detonated, killing 24 men instantly and causing fatal injuries to another two.

Just one man in the dugout survived having been imbedded in the wall by the force of the blast.

Mrs Morris said she had been to many memorial services over the years and had become good friends with the men's relatives, who used to travel to Wagga once a year from all over Australia.

Back in 1945, three days after the tragedy, half of Wagga's population lined the streets to pay their respects to the sappers as the funeral procession passed.

"A lot of the locals heard the noise of the explosion," Mrs Morris said.

Riverina MP Michael McCormack said the young men who died were "part of that long line of khaki which stretches back to Gallipoli right through to today" and they should stay in people's thoughts.

"It is as important as ever that we commemorate what is still regarded as Wagga's darkest day - the largest military training accident on Australian soil and, subsequently, our nation's largest military funeral," Mr McCormack said.

"On 21 May 1945 around 2.45pm, 26 young lives were taken from their friends and families too soon.

"Those young men are no different to the fine young people who currently train at the Kapooka Army Base."

Paddy Cranswick, of Perth, was a trainee sapper at Kapooka in May 1945 and had been due to attend the explosives demonstration but was instead about to depart for compassionate leave.

Mr Cranswick saw the explosion from the base.

"It was a big plume; it went straight up into the air," he told The Daily Advertiser at the Wagga memorial in 2014, which he again visited in 2015 before his death.