He was appointed as a midshipman in October 1841 and immediately was attached to the sloop-of-war USS Warren, which was fitting out at Norfolk Navy Yard in Portsmouth, Virginia, at the time.

Before Warren could put to sea, however, Lewis was transferred to the receiving ship USS Pennsylvania at the navy yard, remaining aboard her for a few months.

In 1850, he transferred to the United States Naval Observatory in Washington, D.C., for a few months, then in 1851 detached to serve aboard commercial steamers of the Collins Line on two or three transatlantic voyages between New York City and Liverpool, England.

He transferred to the new sailing frigate USS Sabine in 1858 and served aboard her during a three-year cruise, during which she took part in the Paraguay Expedition and operated in the West Indies.

He was in command of Nantucket when she closed to destroy a stranded blockade runner with gunfire off Charleston and engaged the Confederate artillery batteries on Sullivan's Island, as well as during later duty at Port Royal, South Carolina, when Nantucket guarded the receiving ship USS New Hampshire in case New Hampshire was targeted by the Confederate States Navy ironclad CSS Stonewall.

[8] In 1865, Lewis joined the staff of the Naval Academy, first as senior instructor in seamanship and later as superintendent of grounds and buildings, and was promoted to commander on 29 January 1867.

Detaching from Kearsarge in November 1875, he returned to the United States and spent four months awaiting orders before reporting for duty as Inspector of Ordnance at the Norfolk Navy Yard.

[4][8][9] On 6 September 1879, Lewis took command of the screw sloop-of-war USS Shenandoah two days before she recommissioned for service in the South Atlantic Squadron as the flagship of Rear Admiral Andrew Bryson.