Born on 24 March 1895 at Leongatha, Victoria, Mackinolty was the son of labourer James Mickleburg Mackinolty and his wife Mary.
He went to public schools, obtaining his merit certificate before undertaking formal engineering and business courses in Melbourne.
Commencing his working life as a coach and motor-body builder, he enlisted in the Australian Military Forces on 17 August 1914, soon after the outbreak of World War I. His experience in the motor industry led to assignment as an air mechanic with the Aviation Instructional Staff at Central Flying School (CFS), Point Cook.
He was soon promoted from private to corporal and later, having gained a reputation for his skill with timber, raised to sergeant and given command of the school's woodworking team.

On 1 August 1915, Mackinolty transferred to the Australian Imperial Force, to lead a team of thirteen other mechanics as reinforcements for an Australian Flying Corps contingent serving in the Mesopotamian campaign.
He departed Melbourne nine days later aboard RMS Persia, and arrived at Basra on 1 September.
Mackinolty's team immediately joined No.
30 Squadron Royal Flying Corps (originally the Mesopotamian Half Flight AFC), which moved into the city of Kut after its capture by British Empire troops in the Battle of Es Sinn.
 The unit took part in the Battle of Ctesiphon in November, and organised supply drops to the British and Indian garrison in Kut during the siege that lasted from December 1915 until the following April.

Mackinolty was promoted in the field to flight sergeant in June 1916, and mentioned in despatches on 19 October.
When the Australian members of No.
 30 Squadron were dispersed, he was posted to Kantara, Egypt, where he joined the newly established No.
 2 Squadron AFC (also numbered No.
 68 Squadron RFC by the British).
Commanded by Major Oswald Watt, the unit relocated to England in January 1917.
Following his service with No.
 2 Squadron, Mackinolty was assigned to No.
 5 (Training) Squadron AFC, which formed at Shawbury, Shropshire, in June 1917.
Praised for his organisational and leadership abilities, he was commissioned as an equipment officer in March 1918, with the rank of second lieutenant.
The following month he was given command of an aircraft repair unit in Minchinhampton, Gloucestershire, home of two squadrons of the AFC's 1st Training Wing.
Born on 24 March 1895 at Leongatha, Victoria, Mackinolty was the son of labourer James Mickleburg Mackinolty and his wife Mary. He went to public schools, obtaining his merit certificate before undertaking formal engineering and business courses in Melbourne. Commencing his working life as a coach and motor-body builder, he enlisted in the Australian Military Forces on 17 August 1914, soon after the outbreak of World War I. His experience in the motor industry led to assignment as an air mechanic with the Aviation Instructional Staff at Central Flying School (CFS), Point Cook. He was soon promoted from private to corporal and later, having gained a reputation for his skill with timber, raised to sergeant and given command of the school's woodworking team.
On 1 August 1915, Mackinolty transferred to the Australian Imperial Force, to lead a team of thirteen other mechanics as reinforcements for an Australian Flying Corps contingent serving in the Mesopotamian campaign. He departed Melbourne nine days later aboard RMS Persia, and arrived at Basra on 1 September. Mackinolty's team immediately joined No. 30 Squadron Royal Flying Corps (originally the Mesopotamian Half Flight AFC), which moved into the city of Kut after its capture by British Empire troops in the Battle of Es Sinn.  The unit took part in the Battle of Ctesiphon in November, and organised supply drops to the British and Indian garrison in Kut during the siege that lasted from December 1915 until the following April.
Mackinolty was promoted in the field to flight sergeant in June 1916, and mentioned in despatches on 19 October. When the Australian members of No. 30 Squadron were dispersed, he was posted to Kantara, Egypt, where he joined the newly established No. 2 Squadron AFC (also numbered No. 68 Squadron RFC by the British). Commanded by Major Oswald Watt, the unit relocated to England in January 1917. Following his service with No. 2 Squadron, Mackinolty was assigned to No. 5 (Training) Squadron AFC, which formed at Shawbury, Shropshire, in June 1917. Praised for his organisational and leadership abilities, he was commissioned as an equipment officer in March 1918, with the rank of second lieutenant. The following month he was given command of an aircraft repair unit in Minchinhampton, Gloucestershire, home of two squadrons of the AFC's 1st Training Wing.
George Mackinolty