John Evan Adlard was born in Surrey, England during 1888. He enlisted in the Australian Imperial Force as a driver on 3 February 1915. Adlard had 4 years prior military service in the Horse Artillery, also as a driver, which contributed to his commission as an officer.

Adlard departed Melbourne with the 1st Division Ammunition Column from Melbourne aboard HMAT Bakara on 14 May 1915. After a stopover in Egypt, he embarked for Gallipoli aboard RMS Snaefell in June 1915. He landed at Cape Helles from the River Clyde. Adlard soon fell ill and was admitted to hospital in Malta on 16 September 1915.

Adlard left Malta aboard the hospital ship HMHT Dunlace Castle on 13 October 1915 and set sail for England. In 12 January 1917, he was admitted for training at the Royal Artillery Cadet School in St John's Wood, England. He was subsequently reassigned to 1st Division Column on the Western Front.

John Adlard was wounded on 23 October 1917 and transferred to England before returning to Australia aboard SS Balmoral Castle on 1 February 1918.