Harrie was one of three brothers in his family who served during World War 1. He was a Clerk with the Commercial Bank at Inverell when, at the age of twenty, he enlisted on 26 May 1915.
Whilst at Inverell Harrie was a keen cricketer and a popular member of the Oxford Cricket Club. His cricket mates organised a smoke concert to farewell Harrie and presented him with a wristlet watch. The Inverell Times newspaper, 25 May 1915, reported that he was also given a Civic Farewell during which the Mayor presented him with a case of pipes.
As a Private with the 19th Batallion, A Company, he sailed for Egypt from Sydney on the ship HMAT Ceramic on 25 June 1915. In March 1916 he was shipped to France where he was killed in action at Pozieres on 26 July 1916.
Private Trenerry was buried at Pozieres British Cemetery, France. His few remaining personal effects - a scarf, mouth organ and handkerchief were returned to his parents at Manilla NSW. His name is recorded on the Inverell Cenotaph.