John William Bonnick was born in East Melbourne in December, 1895, the son of James William Bonnick and his wife, Georgina Jane (Ross). With the permission of his parents, he enlisted on 16 July, 1915, aged nineteen. He had trained with the Senior Cadets and had two years experience with the 58th Infantry. He gave his employment as 'Engineering', having served 2 years with W.H.Allsop, Melbourne, but citing 4 years and 10 months experience. He trained with the 61st Company at Seymour, then joined C Company, then A Company, 29th Battalion, having been transferred on on 3 October, 1915.

The 29th battalion left Australia on 10 November on the HMAT 'Ascania' and was then sent to the front in France via the 'Tunisian', disembarking at Marseilles on 26 June, 1916. Here they marched to the Western Front, where they fought in the Battle of Fromelles, described by one soldier as 'like a bloody Butcher's shop'. John Bonnick was wounded in action, possibly at Delargues Farm,  but chose to remain at his post. The 29th suffered severe casualties, with 52 Men Killed and 164 Wounded and did not engage in major action for the rest of the year. On 3 December, Bonnick was sent to hospital sick, with 'chilled feet', later identified as 'trench foot'and was sent back to the London General Hospital, Wandsworth, for treatment. From here, he was sent on to the 65th Battalion at Wareham, but again hospitalised, this time with influenza on 1 April. During this time, a letter from John Bonnick was published in the Williamstown Advertiser, 8/9/1917, thanking the Anzac Club of Williamstown for the  useful package he received.

With recovery, he returned to the 65th, before proceeding to France via Southampton to rejoin the 29 Battalion  on 11 October, 1917. On 2 November, he rejoined the 29th Battalion at the Western Front near Ypres. At this time, the battle of Bullecourt had been fought and the Germans were planning for the Spring Offensive and the Fourth Battle of Ypres. 

John Bonnick died of wounds on 20 February, 1918, having been taken to the 53 Casualty Clearing Station from the battlefield with a bullet wound penetrating the abdomen. He was buried two days later at Bailleul Cemetery. An entry from the A + D Book of the 53 C C Station read  'On 14/2/18, Pte Bonnick, J.W., 29 Btn, AIF, age 22, Service 2 8/12, Service in Field 18 months, was admitted to No 3 CCS suffering from Bt. Wd. Abd. Pen. and died 20/2/1918.'

On February 6, 1924, his father wrote to the Army, rquesting a permanent headstone be erected over his son's grave, with the inscription 'One of the truest and the best of Australia's heroes, gone to rest'. This was done.