Robert Arthur Jacomb came from a well established East Melbourne family. Robert Elwall Jacomb and his wife, Anne, had first lived in Victoria Parade and then, as their family grew, at 53 Powlett St from the 1860s. Robert Arthur Jacomb was born to their son, Robert Ker Jacomb, and his wife, Louisa, in January, 1886, at Brighton Beach. His mother died at Bendigo on 4 October,1891, and his father on 12 January, 1896 on board the Loch Slay. He was  raised by his grandmother and aunts from the age of five.

Robert Jacomb enlisted early, on 5 January, 1915, but was discharged on request after nine weeks, perhaps owing to an illness of his grandmother's, who was initially nominated as his next of kin and then replaced by his aunt, Lucy Jacomb. He again enlisted on 21 April, 1915, giving his occupation as a farm hand. He was 29 years old, 5' 9" tall, with fair hair, blue eyes and a fair complexion. He was in Liverpool, NSW, at this time and left for Egypt via Sydney. He was taken on strength with the 2nd Battalion, 6th Reinforcements on 15 June, 1915, and died, killed in action at Lone Pine. His body was never recovered.

A death notice in The Argus, 2 September, 1915 reads:                       

Killed in action, at the Dardanelles, between 7th and 14th of August, Robert Arthur Jacomb,                                        son of the late R.K.Jacomb and grandson of Mrs. Jacomb of 53 Powlett St, East Melbourne, aged 29 years.

He is remembered in the Australian War Memorial Roll of Honour, Panel 33 in the Commemoration Area and on the Lone Pine Memorial, Gallipoli, Turkey