John Rohrs was born at St. Helliers in the Channel Islands, probably in December 1882. He was educated at King's School, London where he received two books as prizes, which are still in the possession of his family. He was a keen sportsman, playing both cricket and soccer. His parents had migrated to Australia and lived Gnowangerup, Western Australia, later moving to Bellevue, Tasmania. He was their eldest son. At the time he enlisted on 20 June 1917, he was 33 years old and, on 21 July 1917, he married Edith Grace Matthews. She was the daughter of Richard Matthews, a solicitor who had practised at 45 Wellington Parade, East Melbourne. The family lived at 125b George St., East Melbourne, while John Rohrs gave his current address on enlisting as 125a George St. 

The marriage was announced in The Western Australian of 17 September, 1917: On July 21, at Holy Trinity Church, East Melbourne, by Rev. Newport White. Private John Rohrs of the Australian Flying Corps, eldest son of Mr. and Mrs. Arthur Rohrs, Gnowangerup, to Edith Grace, yougest daughter of the late Mr. and Mrs. Matthews, East Melbourne, Victoria.

Edith Grace (known as Grace) Matthews was 35 years old when she married John Rohrs. She may have already been unwell at this point. On his enlistment form, she is listed C% MCL Convalscent Home, Cottesloe, Western Australia, though she may have been a nurse. She died on 10 December, 1924, aged 48 from appendicitis after refusing a life saving operation due to her beliefs as a Christian Scientist.  She is buried at Northampton Cemetery, Northampton, Western Australia, where John Rohrs was working at the time. On February 24, 1927, he remarried,  this time to  Margaret Thomspon of Subiaco.  They had met in Northampton where John had a farm and Margaret was matron of the hospital. They were to have a daughter in 1928.

John Rohrs was sent for training to the Australian Flying Corps headquarters at Laverton on 25 June, 1917, then had a final week's leave on 21 July before embarking for England with the other Reinforcement Troops. By now he was an Acting Lance Corporal. They set off on HMAT Aeneas A60 from Melbourne, disembarking at Devonport, England, on  26 December, 1917.

John Rohrs had unfortunately caught mumps on the way over and had been hospitalised on board ship from 6-19 December. From Devonport, he was sent to an Isolation Camp at Haldfield, where he remained from 30 December, 1917, until 4 March, when he marched out to AFS Headquarters at Tetbury and was then attached to the 6th Training Squad, Australian Flying Corps, at Wendover. He remained here for the rest of the year.

The war ended on 11 November, 1918, and the return of the troops at the various fronts must have had priority. Whatever the reason, John Rohrs was placed with the No. 1 Training Squad on 3 February, 1919, and remained there until May. He was returned to Australia on 6 May, 1919, on board the Kaiser-i-Hind. He disembarked on 9 June, 1919, and was discharged from further service on 2 July, 1919. On 6 August, he advised the army authorities that his permanent address is Maileeup Border Siding via Gnowangerup, Western Australia, his parents' property.

In 1925, following Grace Rohrs' death, he moved to Kalgoorlie, where he remained for many years as Inspector of the Agricultural Bank. In 1949, he and Margaret were living with their daughter, Margaret Elizabeth, a kindergarten teacher, at Waggrakine (then a tomato growing area but now a north-eastern suburb of Geraldton), where he was working as a sworn valuer. In 1952, he wrote to the army asking for a copy of his discharge papers, which he needed in order to apply for a war service home. By 1954, he was retired and living with Margaret at Lawrence St., Morley Park. He died of oesophageal cancer  in Perth in 1957.  He was a Freemason.