Stevens was born in Newport, Rhode Island on June 9, 1842, the son of Isaac I. Stevens and Margaret Hazard Stevens. In 1854, his father became the first governor of the new Washington Territory and the Stevens family moved to Olympia, Washington. Both father and son volunteered in the Union army during the Civil War and served in the 79th New York Volunteer Infantry. Hazard Stevens was a major and assistant adjutant general. Hazard was wounded and his father, by then a general, was killed in the Battle of Chantilly on September 1, 1862. For his contribution to the capture of Fort Huger, Virginia, on April 19, 1863, Stevens received the Medal of Honor on June 13, 1894. Stevens was mustered out of the Union Army volunteers on September 19, 1865. On January 13, 1866, President Andrew Johnson nominated Stevens for appointment to the brevet grade of brigadier general of volunteers, to rank from April 2, 1865, and the U.S. Senate confirmed the nomination on March 12, 1866.
After the war, Stevens returned to Washington to care for his widowed mother, working initially for the Oregon Steam Navigation Company and then as a federal revenue collector in 1868. He then met P. B. Van Trump, who was working as the private secretary to Marshall F. Moore, the seventh governor of the territory. Both men were interested in climbing Mount Rainier and on August 17, 1870 they completed the first documented ascent of the mountain.
The Stevens Van Trump Historic Monument along the Skyline Trail in Mount Rainier National Park was erected to commemorate the historic first ascent of the mountain. Nearby is the Stevens Canyon and Stevens Ridge, both named after him.
Stevens joined the bar in 1871, representing the Northern Pacific Railroad Company in their prosecution of lumber theft cases. In 1874, Stevens investigated British claims on the San Juan Islands at the request of President Ulysses S. Grant.
In 1874, Stevens moved to Dorchester, Massachusetts near Boston. He then entered the Massachusetts state legislature as a reformer in 1885. He successfully lobbied for the preservation of Boston's Old State House. He was unsuccessful in a run for the United States Congress.
In 1887 Stevens was admitted to the Rhode Island Society of the Cincinnati by right of his descent from Lieutenant Colonel Daniel Lyman.
Stevens climbed Mount Rainier a second time in 1905 on a trip organized by The Mazamas, an Oregon mountaineering club.
Stevens established the Cloverfields Dairy Farm in Olympia, Washington in 1916. Now on the National Historic Register, the former farm is the site of the present Olympia High School.
Later in life, Stevens wrote "The Life of Isaac Ingalls Stevens", a noted biography of his father in addition to many papers on the Civil War. In 1918, while in frail health, he presided over the ceremonial placement of a memorial marker to Bureau of Indian Affairs agent Andrew Bolon in Klickitat County, Washington and, the following day, suffered a stroke of paralysis. He died unmarried shortly thereafter and is interred at Island Cemetery in Newport, Rhode Island Plot: Lots 650-653.
Rank and Organization:
Captain and Assistant Adjutant General, U.S. Volunteers. Place and Date: At Fort Huger, Va., April 19, 1863. Entered service at: Olympia, Washington Territory. Born: June 9, 1842, Newport, R.I. Date of issue: June 13, 1894.
Citation: Gallantly led a party that assaulted and captured the fort.