The scion of a prominent Tasmanian family, Gellibrand graduated top of the Royal Military College, Sandhurst, and was commissioned a second lieutenant in the South Lancashire Regiment (The Prince of Wales's Volunteers) in October 1893.

In May 1900 he was promoted to captain in the Manchester Regiment, and served on St Helena where its primary task was guarding Boer prisoners of war.

Frustrated at the poor prospects for promotion, he resigned his British Army commission in April 1912 and returned to Tasmania to grow apples.

When the First World War broke out in August 1914, Gellibrand offered his services, and was appointed to the First Australian Imperial Force (AIF) as a captain on the staff of the 1st Division.

In June 1940, he was appointed commandant of the Victorian Volunteer Defence Corps, the Australian version of the British Home Guard, but ill-health forced him to resign.

En route she met the ship's surgeon, Dr Edward Clayton Ling, and they were married in Saxmundham, Suffolk, where his family lived, on 28 December 1878.

After a visit to Tasmania with his mother and sister Annie in 1891, he returned to Frankfurt-am-Main in September 1891 to study for the entrance exam to the Royal Military College, Sandhurst.

He graduated at the top of his class of 87 on 18 October 1893, and was awarded the General Proficiency Sword for gaining the highest aggregate marks in the final exams.

He was commissioned a second lieutenant in the South Lancashire Regiment (The Prince of Wales's Volunteers) on 21 October 1893,[8] and was posted to its 1st Battalion, then on garrison duty in Birr, County Offaly, in Ireland.

He attended a course at the School of Musketry in February and March 1895, qualifying him as an instructor in small arms and the Maxim gun, and was promoted to lieutenant on 24 April 1895.

His salary was insufficient to live on, so Gellibrand and Elsie supplemented it by translating German works by Helmuth von Moltke the Elder, Prince Kraft zu Hohenlohe-Ingelfingen and others into English, for which they were paid 10 shillings per thousands words.

He was joined in Durban by Elsie, who had made her way out to South Africa with Cecil Rhodes, and they embarked for England together on 26 May, arriving at Southampton on 18 June.

[14] On 26 May 1900, Gellibrand was promoted to captain in the newly raised 3rd Battalion of the Manchester Regiment, joining his new command at Aldershot on 29 November 1900, where his second daughter, Cynthia Lloyd was born on 22 June 1901.

[20] On 20 August 1914, he was appointed to the Australian Imperial Force (AIF) as a captain, and given the post of Deputy Assistant Quartermaster General (DAQMG) on the staff of the 1st Division.

Patterson had a nervous breakdown and was evacuated on 28 April 1915, Gellibrand performed his job as well until Lieutenant Colonel John Forsyth was appointed AA & QMG on 7 May 1915.

Then, on 11 May, while laughing at two men whose water bottles had been holed, he received a severe wound in his right shoulder and was evacuated to the hospital ship HMHS Gascon.

[28] Gellibrand returned to Anzac on 31 May 1915, to find that Forsyth had been given command of the 2nd Infantry Brigade and Foott, who had been his subordinate, had become AA & QMG and was now his superior.

Dissatisfied, Gellibrand put in for a transfer to the 2nd Division, then being formed in Egypt under the command of Major General James Gordon Legge.

On 1 March 1916 he was again promoted, this time to full colonel and temporary brigadier general,[36] and given command of the 6th Infantry Brigade, on the specific request of Legge.

[43] He was acting commander of the 2nd Division until 5 March 1917,[21][44] directing it in probing attacks against Malt Trench when it was suspected that the Germans were withdrawing to the Hindenburg Line.

[57] On 27 September 1918, the two had a more heated clash during the Battle of the Hindenburg Line over the merits of Gellibrand's intention to attack on a narrow front, something not normally considered advisable.

[60] He was appointed an Officer of the Legion of Honour,[61] and awarded the Croix de Guerre by the French,[62] and the Distinguished Service Medal by the Americans.

He boarded the troopship RMS Kaisar-i-Hind in London on 4 May 1919, and reached Hobart on 30 June, after a long sea voyage, a rail trip from Fremantle to Melbourne, passage across the Bass Strait, and a week in quarantine on Bruny Island due to the 1918 flu pandemic.

Gellibrand felt that urgent action was required to increase force numbers and improve working conditions, but was unable to get his recommendations approved.

[69] Concerned about the plight of fellow ex-servicemen, whose businesses were often failing, Gellibrand banded together with like-minded individuals to form the Hobart Remembrance Club.

The Hobart Club inspired the formation of Legacy Australia in Melbourne, which over time became a national movement, expanding its scope to the care of ex-servicemen's widows and their families.

The Hobart Club did not join Legacy until 1940,[70] but Charles Bean wrote in 1944 that "coming back to the great and good man from whose original work it all sprang—there was a time when some of us thought that the best monument to John Gellibrand might be the story of Second Bullecourt.

As the member for Denison, he supported increased Federal funding for Tasmania, and called for improvements in the way the Australian Army trained future leaders.

He campaigned for an increase in the size of the Australian Army, writing letters to newspapers, and a series of articles for Reveille, the Returned Sailors and Soldiers Imperial League of Australia's organ.

[73] In June 1940, he was appointed commandant of the Victorian Volunteer Defence Corps, the Australian version of the Home Guard, but ill-health forced him to resign in July 1940, to be replaced by Foott.