[4][5][1] She was purchased from William Lamb by the United States Navy on 13 June 1898[1] for service in the Spanish–American War and named for Marcus Claudius Marcellus.

[1] During the Spanish–American War, following a brief cruise along the east coast, Marcellus sailed from Lambert's Point, Virginia on 4 January 1899 to carry coal and supplies to American forces at Havana, Cuba.

[7] In November 1899, outside Sandy Hook,[8] the first real recorded underway replenishment (UNREP) at sea was performed by the U.S. Navy using the Marcellus and the battleship Massachusetts.

The system, devised by Spencer Miller and the Lidgerwood Manufacturing Company of New York, allowed the crew to deliver one 800 pound bag of coal per minute via a cableway strung above the tow cable.

[1] Beginning in January 1900, she operated for five months along the Atlantic coast, carrying coal to Norfolk, Virginia until being placed in ordinary on 4 May 1900[13] for a 30-day repair period.

[7] Marcellus remained in reserve until 25 November 1902, when repairs were finally completed and she again returned to transporting coal along the Atlantic seaboard, the Gulf Coast and ports in the Caribbean.

While the coaling tests at sea achieved a record of thirty five tons an hour steaming at a seven knot speed, the new rig still fell short of Navy expectations.

At 2:30 in the morning on 9 August, while 60 miles off Cape Hatteras, North Carolina, Marcellus was rammed by the Norwegian-flagged fruit steamer Rosario di Giorgio.

The official naval court of inquiry concluded the fault lay with the Rosario di Giorgio, and recommended the government seek recompense from her owners for the value of the Marcellus and her cargo, then placed at US$125,000.