Over the next three years, Wyman served in South American waters in the schooner, the brig, and the frigate before participating in the Mexican–American War in Commodore Conner's Home Squadron—first in the steamer and later in the brig and the sloop. During that time, he took part in the expeditions against Tampico during November 1846 and Veracruz in March 1847. Passed Midshipman, Wyman spent a tour of duty ashore at the Naval Observatory, Washington, D.C., before reporting to the receiving ship at Boston, Massachusetts, and subsequently being promoted to lieutenant on 16 July 1850. Over the next decade, he served at sea; and the outbreak of the Civil War in April 1861 found him in command of on the Mediterranean Station.
Early in July, soon after he brought that steam sloop-of-war home for wartime duty, he took command of. In September, Wyman assumed command of. That ship, as part of the Potomac River Flotilla, helped to keep open the Union's vital waterway communications with Washington, D.C., while cutting off Southern forces from their sympathizers in southern Maryland. Commanding the steamer from October 1861, Wyman took part in Flag Officer DuPont's capture of the key seaport of Port Royal, South Carolina. After that operation, Wyman returned north and took command of the Potomac River Flotilla on 6 December 1861. He held this important post until the end of June 1862. During his time in the Potomac, he was active in maintaining Union control of that vital river and of much of the Rappahannock during General McClellan's Peninsular Campaign. His ships destroyed Southern bridges, captured nine Confederate ships, and burned 40 schooners. Promoted to commander on 16 July 1862, Wyman was ordered to command the gunboat on the James River. Transferred to the West Indian Squadron the following October, he commanded the steam sloop and the paddle steamer, and captured the blockade runners and Lizzie. During the last two years of the Civil War, Wyman served on special duty in the Navy Department in Washington, D.C.
Later career
After the Civil War, Wyman commanded, the flagship for the European Squadron. He was promoted to captain on July 25, 1866, and took command of the steam sloop the following year. After that tour of sea duty, Wyman headed the Navy's Hydrographic Office for eight years, receiving promotions to commodore on July 19, 1872, and to Rear Admiral on April 26, 1878. His leadership of the Hydrographic Office proved to be of great importance to the Navy and seafaring men in general. Through the Civil War, the United States Navy had relied upon foreign sources—principally British—for their navigational charts, doing little of their own hydrographic work. Under Wyman's direction, the office began a systematic and sustained program of worldwide charting and surveying, the precursor of the navy's present globe-girdling oceanographic research effort. Wyman was given command of the North Atlantic Squadron in January 1879, leaving in on May 25, 1882, to become a member of the Lighthouse Board. Rear Admiral Wyman died in Washington, D.C., on December 2, 1882.
