After training at Ingleburn and Bathurst, his battalion embarked for the Middle East on 19 October 1940 as reinforcements for the 9th Division.

On the night of 13th–14th April, 1941, a party of German infantry broke through the wire defences at Tobruk, and established themselves with at least six machine guns, mortars and two small field pieces.

It was decided to attack them with bayonets, and a party consisting of one officer, Corporal Edmondson and five privates, took part in the charge.

During the counter-attack Corporal Edmondson was wounded in the neck and stomach but continued to advance under heavy fire and killed one enemy with his bayonet.

His actions throughout the operations were outstanding for resolution, leadership and conspicuous bravery.An hour later, 200 German infantrymen attacked the post, forcing the Australians to withdraw, and established a bridgehead in the outer defensive line.

[4] His name is still honoured by: the John Edmondson VC Rest Area at Roses Lagoon on the Remembrance Driveway from Sydney to Canberra; John Edmondson VC Memorial RSL Club, Liverpool, NSW; a plaque in the Walk of Honour in Baylis Street, in his birthplace of Wagga Wagga, NSW; the school hall in his former school, Hurlstone Agricultural High School, is named after him; a high school in the Horningsea Park district in NSW is named after him; the Sydney suburb of Edmondson Park, and Edmondson Street in the Sydney suburb of North Ryde, are named in his honour.