The Bureau of Steam Engineering was a bureau of the United States Navy, created by the act of 5 July 1862, receiving some of the duties of the former Bureau of Construction, Equipment and Repair. It became, by the Naval Appropriation Act of 4 June 1920, the Bureau of Engineering (BuEng). In 1940 it combined with the Bureau of Construction and Repair (BuC&R) and became the Bureau of Ships (BuShips).
"Engineering, both in operating the shipboard machinery and in the design and construction of ships, became critically important with the outbreak of the Civil War. The Navy had to blockade a ‘coastline stretching over 3, 000 miles from the Potomac to the Mexican border. It had to support the Army on the rivers; it had to search out and destroy Confederate raiders. For all these purposes, the steam engine and the engineer were indispensable. On the day of battle, steam engines drove the Monitor and the Merrimack, the Kearsarge and the Alabama, as well as the gunboats which supported Grant before Fort Donelson and Vicksburg. In 1862, Congress recognized the importance of engineering by creating the Bureau of Steam Engineering.
"When Lee surrendered, the United States Navy was the most effective sea power in the world. That position depended upon engineering which, in turn, was based on the skill of Benjamin F. Isherwood, first Chief of the Bureau of Steam Engineering. He designed and built engines rugged enough to withstand the shock of combat, as well as ill-treatment by poorly trained operating engineers. He also designed and constructed a well-armed cruiser which was faster than any abroad. In addition, American naval leadership rested upon ingenious civilian engineers and inventors such as John Ericsson, who designed and built the Monitor."
The Navy's first marine engineer was a civilian appointment in 1836. Congress authorized the establishment of an Engineer Corps in 1842. The 1862 reorganization gave officers of the Engineer Corps their own bureau with dedicated billets to avoid competition from Construction Corps officers (naval architects) in the separated Bureau of Construction and Repair. In 1864 Congress authorized establishment of a separate United States Naval Academy curriculum for naval constructors and steam engineers; and the academy offered parallel tracks for cadet-midshipmen and cadet-engineers. Shipboard commanding officers became uncomfortable with their increasing dependency on the skills and advice of subordinates trained in matters unfamiliar to them; so a common naval academy curriculum was re-instituted in 1882, and Engineer Corps officers were merged into the unrestricted line in 1899. Junior Engineer Corps officers qualified for general line duties at sea, and senior Engineer Corps officers were restricted to shore assignments in their specialties. The restricted line officer concept of "engineering duty only" (EDO) was revived in 1916 when the Engineer Corps officers proved inadequately prepared for the expanded shipbuilding programs of World War I. The EDO designation expanded to include naval architects of the former Construction Corps when the two Corps were merged into the Bureau of Ships in 1940.