Robert Casey was born in Battery Point, Castle Forbes Bay, Hobart, Tasmania on 2 June 1900. He was the son of William Francis Casey and Lavinia Jane Casey (née Thorp) and their large family. He joined the Australian Naval College as a Cadet in 1914. He was promoted to Midshipman with seniority of 1 January 1918 and, on 28 April 1918 he was appointed to the battlecruiser HMAS AUSTRALIA in which he served until 17 September 1919.

After volunteers were called for to man the ‘J’ Class submarines – following their being ‘gifted’ to the Royal Australian Navy – Robert Casey volunteered and was appointed to the Submarine Depot ship HMAS PLATYPUS on 25 September 1919 for a three-month Submarine training Course. On completion of the course he was appointed to HMAS J2 in which he served until 23 April 1921. An appointment to HM Australian London Depot followed on 27 July 1921 and to the Royal Naval College, Greenwich ‘for his Lieutenant’s courses’.

Robert then served in the cruisers HMAS SYDNEY, HMAS BRISBANE and HMAS MELBOURNE from 17 December 1922 to 6 June 1924. He next served in HMAS PENGUIN (which was the re-named Submarine Depot Ship HMAS PLATYPUS) until 3 March 1925 and then returned to HMA London Depot before joining HMS DOLPHIN on 27 March 1925 ‘for Submarine courses’. In June 1925 he was appointed to HMS M1 ‘as 3rd Hand’. M1 was lost with all hands on 12 November 1925 following a collision whilst the submarine was dived with the Merchant Vessel SS VIDAR off Portland. 

Note. It is understood that it had been intended that Robert Casey would be trained up and qualified to be the ‘Spare Commanding Officer’ for the Australian ‘O’ Class submarines OA1 and OA2 (later renamed OTWAY and OXLEY) but that this plan was not possible owing to his loss in M1.