Bill -- William Sooy Smith is my 2nd great granduncle. I found a picture of him online and he bears a remarkable resemblance to my younger son. (Things like that make genealogy really fun!)
Here's some of what I've learned about him:
Born in Tarlton, Pickaway Co., Ohio July 22, 1830. Graduated at Ohio University in 1849 and from the U.S. Military Academy in 1853. Resigning from the army in 1854, he bacame assistant to Lt.Col. James D. Graham of the U.S. topographical engineers, then in charge of the govt. improvements in the Great Lakes. In 1855 he moved to Buffalo, NY and for a while was principal of a high school. In 1857 employed by city of Buffalo as an expert to examine the various plans submitted for the international bridge across the Niagara River. Later became engineer and secretary of the Trenton, NJ locomotive works, until 1861. He visited Cuba in the interests of this company and also constructed an iron bridge across the Savannah River, where he introduced improvements in sinking cylinders pneumatically. In 1861 he was appointed lieutenant-colonel of Ohio volunteers and assigned as assistant adjutant-general at Camp Dennison. Comissioned colonel of the 13th Ohio infantry June 26, 1861, took part in the campaigns of western Virginia, then entered the Army of the Ohio and was present at Shiloh and Perryville. Became brigadier-general of volunteers, April 15, 1862, when he joined the forces under Grand and participated in the Vicksburg campaign as commander of the 1st division of the 16th Corps. Later made chief of cavalry of the Department of the Tennessee, and attached to the staff of Gen. Grant and Gen. Wm. T. Sherman until failing health compelled his resignation Sept, 1864.
Resuming his profession after the war, he built the Wangoshanee lighthouse at the entrance of the Straits of Mackinaw where he sank the first pneumatic caisson in 1867. He built the first great entire steel bridge in the world, across the Missouri River at Glasgow, MO and was concerned in construction of many others, incl. those at Leavenworth, KS and Omaha and Plattsmouth, NE. He was president of Civil Engineers Club of the Northwest in 1880.
He died in Oregon in 1916. I think in Medford, but I'm not positive.
If you put his name into a search engine like Google you should get more info.