Born in Medonte Township, Upper Canada, the son of Elmes and Anne Steele, Sam Steele received his education at the family home, Purbrooke, and later at the Royal Military School, father had died when thirteen leaving him orphaned.
Samuel Steele's family had a strong military tradition, and in 1866 he joined the militia during the Fenian Raids. Steele also participated in the Red River Expedition in 1870 to fight the Red River Rebellion of Louis Riel. Much to his disappointment, he arrived after the Métis had surrendered. The following year he joined the Permanent Force artillery, Canada's first regular army unit. Steele had long been fascinated by the West, devouring the works of James Fenimore Cooper in his youth. He was especially interested in the First Nations, and spent his time in the West learning from them and the Métis. However, he was assigned to Fort Henry in Kingston, Ontario, for the next few years, as an instructor at the Artillery School.
In 1873, Steele was the third officer sworn in to the newly formed North-West Mounted Police (NWMP), entering as a staff constable. He was one of the officers to lead the new recruits of the NWMP on the 1874 March West, when he returned to Fort Garry, present-day Winnipeg, Manitoba. To him fell the rank of staff sergeant major and the responsibility—as an accomplished horseman and man-at-arms—of drilling the new recruits. In 1878, Steele was given his own command at Fort Qu'Appelle, Saskatchewan.
In 1877, he was assigned to meet with Sitting Bull, who, having defeated General Custer at Little Bighorn, had moved with his people into Canada to escape American vengeance. Steele along with U.S. Army General Alfred Howe Terry attempted unsuccessfully to persuade Sitting Bull to return to the United States. (Most of the Sioux did return a few years later.)
During the North-West Rebellion Steele was dispatched with a small force. Missing the Battle of Batoche the Mounties were sent to move against the last rebel force led by Big Bear. He was present at the Battle of Frenchman's Butte, where Big Bear's warriors defeated the Canadian forces under General Thomas Bland Strange. Two weeks later, Steele and his two dozen Mounties defeated Big Bear Canadian territory. The contributions of the NWMP in putting down the rebellion went largely ignored and unrewarded, to Steele's great annoyance. By 1885, Steele held the rank of superintendent. He established a NWMP station in the town of Galbraiths Ferry, which was later named to Fort Steele after Steele solved a murder in the town. He then moved on to Fort Macleod in 1888. He married Marie Harwood at Vaudreuil, Quebec in 1890 (they had met at Fort Macleod the previous year). They had three children, including Harwood Steele, who would fictionalize episodes from his father's life in novels such as Spirit-of-Iron (1929).
The discovery of gold in the Klondike, Yukon, in the late 1890s presented Steele with a new challenge. Although he campaigned unsuccessfully for the position of assistant commissioner in 1892, in January 1898, he was sent to succeed Charles Constantine as commissioner and to establish customs posts at the head of the White and Chilkoot Passes, and at Lake Bennett. He was noted for his hard line with the hundreds of unruly and independent-minded prospectors, many of them American. To help control the situation, he established the rule that no one would be allowed to enter the Yukon without a ton of goods to support themselves, thus preventing the entry of desperate and potentially unruly speculators and adventurers.
Steele and his force made the Klondike Gold Rush one of the most orderly of its kind in history and made the NWMP famous around the world, which ensured its survival at a critical time when the force's dissolution was being debated in Parliament. By July 1898, Steele commanded all the NWMP in the Yukon area, and was a member of the territorial council. As the force reported directly to Ottawa, Steele had almost free rein to run things as he chose, always with an eye towards maintaining law, order and Canadian sovereignty. He moved to Dawson City in September 1898.
Always a soldier, in 1900 Steele leapt at the offer of Canadian Pacific Railway tycoon Lord Strathcona to be the first commanding officer of Strathcona's privately-raised cavalry unit, Lord Strathcona's Horse. This Canadian light cavalry unit, in British Imperial service, was sent to South Africa during the Second Boer War, where Steele commanded them with distinction in the role of reconnaissance scouts. Steele, however, disliked greatly what he was ordered to do by the British, which included burning towns and moving the populace to concentration camps. After taking the unit back to Canada early in 1901, Steele returned to South Africa that same year to command 'B' Division of the South African Constabulary, a position he held until 1906. On his return to Canada in 1907, Steele assumed command of Military Division No. 10 (Winnipeg), where he spent his time regrouping Lord Strathcona's Horse and in preparing his memoirs.
Steele requested active military duty upon the outbreak of the First World War. He was initially rejected for command on the grounds of age. However, a compromise was reached which allowed him to act as commander of the 2nd Canadian Division until the unit was sent to France, whereupon he would be replaced. After accompanying the division to England, Steele was offered an administrative post as commanding officer of the South-East District.
Matters were complicated, however, when Canadian Minister of Defence Samuel Hughes insisted that Steele also be made commander of all Canadian troops in Europe—a slight problem, as there were two brigadier-generals who each believed the Canadian command was theirs. The issue was not resolved until 1916, when the new Minister of Overseas Military Forces of Canada, Sir G. H. Perley, removed Steele from his Canadian command after Steele refused to return to Canada as a recruiter. He kept his British command until his retirement on 15 July 1918. While in Britain, Steele was knighted, on 1 January 1918, and was made a Companion of the Most Honourable Order of the Bath, Knight Commander of the Most Distinguished Order of St. Michael and St. George, and Member of the Royal Victorian Order. Steele died of influenza just after his seventieth birthday and was later buried in Winnipeg.
Canada's fifth tallest mountain, Mount Steele, is named after him.
Steele's papers, believed by historians to contain a wealth of heretofore untold stories that would "re-write Canadian history" had been held by British descendants of Steele, and were returned to Canada via a C$1.8MM purchase by the University of Alberta.
Hector Adair, a character in the novel Spirit-of-Iron (1923), written by Steele's son, Harwood Steele, is thought to have been modelled on the famous Mountie. The novel includes a foreword in which the author writes: "Hector Adair is intended to represent the ideal Mounted Police officer in particular and the British officer generally. He is not to be identified with any historical figure connected with the Force."
Players meet Sam Steele in the 1994 computer simulation game The Yukon Trail.
In James Michener's Alaska, "Major Sam Steele" is the face of the NWMP. Michener acknowledges him as a historical figure in the notes at the start of the book, but the veracity of his claimed actions is unknown.
In the television series Due South, "North'" (Season 2, Episode 123, 1995), Fraser references Sam Steele as having been very proud of never firing his weapon while patrolling the Northwest Territories.