Thacker was born the son of Major-General J. Thacker of the Bombay Staff Corps in 1870 in Poona, India. His attended Upper Canada College in Toronto and, in 1887, he graduated from the Royal Military College of Canada. Commissioned in the Royal Canadian Artillery in 1891, he conducted survey work in western Canada for the Canadian Pacific Railway. He was promoted to Lieutenant in 1893. His service in the Second Boer War of 1900 in the Canadian Field Artillery led to the award of the Queen's medal with three clasps. From 1904 to 1905 he had the unique Canadian assignment as a military attaché with the Japanese Army during the Russo-Japanese War but he was joined by other colonials. Along with other Western military attachés, Thacker had two complementary missions – to assist the Japanese and to observe the Japanese forces in the field during the Russo-Japanese War. In 1907, his appointment as Director of Artillery at Ottawa accompanied a promotion as Commanding Officer of the Royal Canadian Garrison Artillery, and he became one of the 65 to live in the Commanding Officers’ Residence at Royal Artillery Park in Halifax. In 1911 he became Inspector of Coast Defense Artillery. At the outbreak of World War I, Thacker joined the Canadian Expeditionary Forces, sailing for Europe with the 1st Canadian Division. Thacker went on to command the 2nd Canadian Divisional Artillery from 1914 to 1915. After General Sir Henry E. Burstall was promoted, Thacker commanded the 1st Canadian Divisional Artillery from September 1915 through the end of World War and the CEF return to Canada. After the war, Thacker was appointed the District Officer Commanding Military District 6, returning with his family to live at Royal Artillery Park. His career was capped with service as Chief of the General Staff from 1927 to 1929. Thacker retired from military service in 1929. He died in Victoria, British Columbia, in June 1953.
Honors
For his service in the Boer War, Thacker was awarded the Queen's Medal with three clasps. He was awarded the Order of the Sacred Treasure, Third Class by the Japanese government for his services during the Russo-Japanese War. He also received the Japanese War medal for service during that campaign.
