Arthur Arundel Mackenzie was born at Greta, New South Wales, on 12 April 1891. Sadly, he lost his mother when he was about six years old. Before the First World War he spent several years in the senior cadets and at the time of enlisting was a member of the local rifle club at Guyra, New South Wales. The 24-year-old station manager enlisted with the Australian Imperial Force on 12 August 1915 and departed Sydney with reinforcements for the Imperial Camel Corps (ICC) aboard RMS Morea on 27 May 1916.

Having arrived in Egypt, Mackenzie was assigned to the 4th Company of the 1st Australian Battalion of the ICC. Sadly, the start of his service also marked the end of his brother's service: Ronald Mackenzie was killed in action at Pozières. Shortly after the second battle of Gaza in April 1917 Mackenzie was wounded in action with a gunshot to his right leg. After recovering, he rejoined his unit as it advanced through Palestine and towards Gaza.

In April 1918, in one of the last actions of the ICC, Mackenzie fought to defend the hill at Mussallabeh. Some of the Australians ran out of hand grenades and resorted to heaving boulders down upon the attacking Turks. Mackenzie and his outnumbered group of men put up a vigorous and determined resistance and succeeded in forcing a retreat. For his actions at Mussallabeh Mackenzie was awarded the Military Cross. After battling several bouts of malaria, he was transferred to the 14th Light Horse Regiment and served with the unit until the end of the war. The Syria campaign had ended and from his letters home it is clear he was deeply affected by the hardships that the country's starving people had endured throughout the war.

Mackenzie returned to Australia as an honorary captain at the end of 1919, and his appointment with the AIF was terminated on 8 April 1920. He later served with the 3rd Volunteer Defence Corps during the Second World War. Arthur Mackenzie died at Guyra in 1970.