Eldest son of Herbert Gregory Ballantyne and Edith Emily Ballantyne, of Puketpapu, Hawke's Bay, New Zealand. His father at the time of his birth owned the store at Puketapu and later bought a farm in the area.

Corporal Ballantyne started school at Puketapu in 1913, passed his Matriculation examination at Hastings Boys High School, and then joined the Army Cadets for three years. At the time of enlistment he was self-emplyed as a farm contractor.

On the 1st November 1939 he marched out to join 2nd Division, Supply Column at Burnham Camp. He was admitted to Christchurch Hospital on 6th November 1939 until 24th November 1939, returning to Burnham Camp.

On 16 December 1939, he married Jessie Sainsbury, a registered nurse from Waipukurau, Hawke's Bay.

Embarking for Egypt on 13th February 1940 as part of the 4 Field Ambulance, Ballantyne was received at Base Reception Depot on 24th April 1940 he was sent to Alexandria to take delivery of ambulances, rejoining his unit on 27th April.

On 27th April 1940 he went to duty with the Scots Guards at Kasr El Nil. On 7th June 1940 he was promoted to Corporal, and on 3rd September he was reassigned to A Company.

Corporal Ballantyne was mortally wounded by bomb fragments during an enemy bombing raid on the oasis of Maaten Burbeita, on 19th October 1940 whilst. One other driver from 4 Field Ambulance was killed, and two others were injured; these were the unit's first casualties.

A Memorial stone, St Matthews Church, Hastings, New Zealand was dedicated Sunday 22 April 1951.

A Memorial plaque, at Puketapu Church, Hawkes Bay, New Zealand has the inscription: "To the glory of God and in loving memory of CPL Peter Grant Ballantyne, NZASC killed in action 19th October 1940 aged 32 years, greater love hath no man than this, we will remember them". AWMM