Per his military service record (regimental no. 4729), Robert Ayres was born at Surrey Hills, N.S.W. He gave his age as 41 years and 11 months, his marital status as married, and his occupation as cab driver. His description on his Certificate of Medical Examination was height 5 feet 5 ½ inches tall, weight 140 lbs., with a fair complexion, blue eyes, and fair hair. His religious denomination was Wesleyan. He claimed to have no previous military service.
He completed his medical examination at Ashfield on 11th November 1915. He was attested by Lieutenant F. Middenway when the Coo-ees were at Ashfield on 11th November 1915.
After completing the Coo-ee March he went to Liverpool Camp as reinforcement for the 13th Battalion.
On his embarkation roll his address at time of enrolment was 2 Mill Street, Croydon, N.S.W. His next of kin was listed as his wife, Mrs M. [Martha] Ayres, at the same address.
On 8th March 1916 Private Ayres, along with many of the other Coo-ees, departed Sydney on the HMAT A15 Star of England. He arrived in Egypt on 11th April 1916.
On 7th of June 1916 Private Ayres left Alexandria aboard the H.T. Ionian bound for France. He arrived at Marseilles on 14th June 1916.
He joined the 13th Battalion in France on 19th August 1916.
Ten days later, on 29th August 1916 the 13th Battalion was in action around Mouquet Farm, France. During the previous 24 hour period the 13th Battalion was under heavy artillery fire, and had suffered a total of 18 killed, 99 wounded and 33 missing. Private Ayres was one of those wounded, being evacuated to a Casualty Clearing Station suffering Shell Shock.
On 6th September 1916 Private Ayres was sent to the 3rd Convalescent Depot at Etaples, France.
On 9th September 1916 he marched into the 4th Australian Division Base Depot at Etaples.
On 7th January 1917 Private Ayres re-joined the 13th Battalion when it was at Mametz, France.
On 29th January 1917 Private Ayres was detached for duty at the Corps Baths at Heilly, France.
On 20th April 1917 Private Ayres was sent to hospital. He re-joined the 13th Battalion on 26th April 1917, when it was training at Ribemont, France.
On 14th September 1917 Private Ayres was detached from the 13th Battalion for duty at the 4th Australian Division Base Depot at Le Harve, France. He arrived on 16th September 1917.
On 26th September 1917 Private Ayres was transferred to England. He arrived at Weymouth, England, on 27th September 1917, where he marched into the No. 2 Command Depot.
Private Ayres departed England on 31st October 1917 for return to Australia, suffering senility, aboard the H.M.A.T. Berrima.
He disembarked at Sydney on 31st December 1917.
Private Ayres was discharged medically unfit on 31st January 1918.
 NAA: B2455, AYRES R
 Australian War Memorial. First World War Embarkation Roll, Robert Ayres, 4729.
 Australian Imperial Force unit war diaries, 1914-18 War – AWM4 Subclass 23/30 – 13th Infantry Battalion, August 1916.
 Australian Imperial Force unit war diaries, 1914-18 War – AWM4 Subclass 23/30 – 13th Infantry Battalion, January 1917.
 Australian Imperial Force unit war diaries, 1914-18 War – AWM4 Subclass 23/30 – 13th Infantry Battalion, April 1917.