Allan Campbell (SN 401) was born in St Kilda and was a 29-year-old grazier when he enlisted in Adelaide on June 10th 1915. He moved swiftly through the ranks and had attained the rank of provisional Company Sergeant Major by the time he embarked from Adelaide aboard the Geelong on November 18th to serve with the 32nd Battalion. In May 1916 he was commissioned as a 2nd Lieutenant before reaching France in June. He was wounded in action at Fromelles on July 19th and was evacuated to hospital in England for treatment to a head wound. He rejoined his unit in France in September, and by April 1917 he had risen to the rank of Captain. Outstanding bravery and devotion to duty on several occasions in 1917 and early 1918 earned for him a Military Cross. He was also recommended for the French Legion d’Honneur but this award was never ratified. After the war he returned to Australia aboard the Derbyshire, disembarking in April 1919.

His older brothers James, who is also honoured with a tree in the Avenue, and Norman also served, having previously served in the Boer War.