Born in Castlemaine, Victoria, Arthur Harold Mars was a single 18 year old blacksmith at the time of his enlistment on the 28th of July 1915. His unit embarked from Melbourne, Victoria, on board HMAT A64 Demosthenes on the 29th of December 1915.
On the 12th of August 1916, Arthur was wounded in action. He rejoined his unit on the 23rd of October 1916.
On the 18th of November 1917, Arthur returned to Australia and was discharged on the 28th of December 1917 as medically unfit due to heart troubles.

His brother Stanley was killed in action on April 27th 1915 and his brother Conrad also served in the AIF and they are honoured with trees in the Avenue. Also his step-brothers Frederick, Valentine, and John Stradling also served in the AIF and are honoured with trees in the Avenue.