He worked in various parts of Australia before heading to New Guinea, intending to earn funds for the return journey to England via New Zealand, India and Africa.

Matters changed with the outbreak of the First World War; he joined the Australian force formed in New Guinea for the defence of the area in the face of German warship activities.

He was 23 years old, and a sergeant in the 5th Machine Gun Company, 5th Brigade, 2nd Division when the following deed took place for which he was awarded the VC.

Sergeant Castleton went out twice in the face of this intense fire, and each time brought in a wounded man on his back.

[2]Castleton is buried at Pozières British Military Cemetery, Somme, France, 3 miles NE of Albert (Plot IV, Row L, Grave 43).