William Ames was born on May 15, 1842, in Providence, Rhode Island, to Samuel and Mary Ames. His father was the chief justice of the Rhode Island Supreme Court. He grew up and attended school in Providence.
In June 1861, he received a commission as a 2nd lieutenant in Company D of the 2nd Rhode Island Infantry. The regiment took part in the First Battle of Manassas, the Peninsula campaign, and the Battle of Fredericksburg. He was promoted to 1st lieutenant in October 1861 and to captain in November 1862.
In February 1863, he was promoted to major in the 3rd Rhode Island Heavy Artillery. The regiment took part in the siege of Charleston. He was promoted to lieutenant colonel in March 1864 and finally to colonel in October 1864. He mustered out on August 27, 1865.
He returned to Providence after the war, and he worked as an internal revenue collector. By 1870, he owned $9,000 of real estate and $2,000 of personal property. He married Harriette Ormsbee on November 8, 1870, and they had at least three children: John, born around 1872; William, born around 1873; and Harriette, born around 1875. His wife died on February 14, 1875. By 1880, he was working as a cotton manufacturer.
He married Anne Carrington on April 27, 1882. He travelled abroad in 1899, 1903, and 1905. He became a prominent member of Providence society, and he served as president of the Blackstone Canal National Bank. He died in Providence on March 8, 1914.