He was the son of William Heenan, a civil servant with the Board of Trade in Belfast. Thomas George was working as a journalist in Belfast at the time of the 1911 census but was then admitted to the civil service and followed his father into the Board of Trade.
In June 1915 he was designated as a temporary Second Lieutenant in the 4th Battalion and attached to the 1st Battalion of the Royal Dublin Fusiliers. He served in France until his death on the Somme during the Second Somme Offensive. This is officially recorded as March 21, 1918 but is not a definitive date since he had been reported missing and this is date when it seems the army determined he could not be located and was presumed dead. According to army records he was 23 years old.
The day of his death was marked by a heavy and sustained attack by the German forces during the offensive called ‘Operation Michael'. This was a major German military offensive during the First World War that began the Spring Offensive on 21 March 1918. It was launched from the Hindenburg Line, in the vicinity of Saint-Quentin, France. Its goal was to break through the Allied lines and advance in a north-westerly direction to seize the Channel ports, which supplied the British Expeditionary Force (BEF) and to drive the BEF into the sea. Much of the ground fought over was the wilderness left by the Battle of the Somme in 1916.
At the end of an assault lasting five hours which involved gas and explosives, the 1st Battalion of the Fusiliers retreated. Six hundred soldiers were missing, leaving the battalion with only five officers and ninety men.
Thomas George Grandon Heenan is commemorated on the Pozieres Memorial in France, on panels 79 and 80. He was awarded posthumously the British Medal and the Victory Medal.
He is also commemorated on the Roll of Honour listing the 305 employees of the Board of Trade who lost their lives during the war. The Roll was initiated by the Board's staff and unveiled on 19 December 1923, by the Prime Minister, Stanley Baldwin, a former President of the Board of Trade.
His parents were living at 42 Derwent Road, Stoneycroft, Liverpool at the time of his death. The family subsequently returned to Ireland where William Heenan died in County Cork in October 1932 and his wife Kathleen a few months later, in December 1932. They had no living children.
Details of the German offensive can be found at Wikipedia via this link
Details of his family can be found in the database by searching for person ID I379 or clicking here