Stewart Blacker was born on 4 July 1865 at Marholm in Northamptonshire, the third of the three sons of Reverend Robert Shapland Carew Blacker and Theodosia Sophia Charlotte (née Meara). His father was the rector of the 12thC parish church of St. Mary the Virgin.
He was commissioned into the Royal Regiment of Artillery from the Royal Military Academy, Woolwich in 1885. His first period of operational service was on the North West Frontier in August 1897, when he commanded the guns of 51st Field Battery at Shabkadr; he was severely wounded in the thigh and mentioned in despatches. He served during the South African War in the Natal Field Force. Blacker was promoted to Major in 1900. He retired on 3 May 1905.
On 6 January 1903, he married Eva Mary Lucy St. John FitzRoy and the family resided at the Blacker family home at Carrick Blacker, near Portadown in County Armagh. Stewart Blacker was a leading figure in the anti-Home Rule movement and in the Ulster Volunteer Force—he was one of the first signatories of the Ulster Covenant in Portadown on 28 September 1912 and he raised and commanded the 4th (Portadown) Battalion of the Armagh Regiment of the Ulster Volunteer Force in 1912.
Recalled for service in August 1914 when war broke out, he was posted initially to Edinburgh. On 15 September 1914 he transferred to Princess Victoria’s (Royal Irish Fusiliers), was promoted to Temporary Lieutenant Colonel, and appointed to command the 9th (Service) Battalion, Princess Victoria’s (Royal Irish Fusiliers) (County Armagh). The Battalion largely comprised men of the Ulster Volunteer Force from Counties Armagh, Cavan and Monaghan, many of whom were known personally to Blacker. He commanded the Battalion in France and Flanders from October 1915 to March 1917. For this he was awarded the DSO, mentioned in despatches three times, and was made an Officer of the Legion d’Honneur and awarded the Croix de Guerre (France). He subsequently commanded the 20th (Reserve) Battalion, The Royal Irish Rifles at Newtownards from 18 April 1917 until 16 May 1918, when he retired. He was made Brevet Lieutenant Colonel in June 1918.
Stewart Blacker settled in Walditch and, from 1930, in Chideock in Dorset. He died after swimming in the sea at Seatown on 6 September 1935, aged 70. His eldest son, Lieutenant Colonel William Desmond Blacker DSO, was killed in action by mortar fire on 11 July 1944 in Normandy while commanding 179th Field Regiment, Royal Regiment of Artillery, having taken command on 3 July. His second son, Commander Robert Stewart Blacker, served during the Second World War with the Royal Navy. A third son, Terence F. Blacker, died in 1932, aged 21. His eldest daughter, Betty Mary Blacker, was the wife of Rear Admiral George Arthur Thring CB, DSO*. His second daughter, Joan Lucy Blacker, married later in life (Dr James Craig McMaster, a well regarded obstetrician and gynecologist) and also lived in Dorset.
Stewart Blacker’s remains were cremated and the ashes interred at Woodbrook House, Enniscorthy in County Wexford, the family seat. His eldest son is buried in St. Manvieu War Cemetery, Cheux, France.