Her duties consisted of patrolling these waters to safeguard their use as lines of communication and supply supporting Union troops then pushing south through the state of Tennessee and, later in the war, into Georgia.

As they ascended that river, they destroyed "... every kind of boat that could serve the rebels..." On the 11th, she, Covington, and Silver Cloud left Queen City and Champion, the division flagship, at Cerro Gordo and continued on upriver to Eastport, Mississippi, ".

Their presence far up the Tennessee River provided General William Rosecrans with a possible haven of naval gunfire support to which his troops could retire in the event of a serious setback in an engagement with Confederate forces which, Union leaders then felt, were massing for a major offensive.

For a number of reasons – including the assassination of General Earl Van Dorn on 7 May – the Southern push did not materialize, but Argosy's operations on this occasion were typical of her service throughout the remaining two years of the Civil War.

In the predawn darkness of 24 April, the Confederate steam ram Webb – which had just emerged from the mouth of the Red River – dashed downstream past Argosy in an attempt to escape to sea.

When her true nature was discovered and a warning of her coming had been wired downriver, her commanding officer, Lt. Charles W. Read, CSN, realized that all chance of safely reaching the Gulf of Mexico had disappeared.