Assigned as a supply ship and gunboat on Southern rivers

On 3 April, she got underway up the Ohio River to join a group of gunboats – commanded by Lt. Comdr. Le Roy Fitch – operating on that river and on its tributaries, the Tennessee River and the Cumberland River. 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. She also labored to deny the use of these waters to Southern forces.

Leaving behind a path of destruction

For example, on 5 May, she joined four other gunboats in an expedition up the Tennessee River. 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, ". . . the highest navigable point at that stage of water."

Providing reserve support for General Rosecrans

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.

By this time, the South's naval forces had been swept from the Mississippi River and its branches; and Vicksburg, Mississippi, and Port Hudson, Louisiana, the last Confederate riverside forts blocking Northern shipping, were about to fall. Thus, other than routine patrol and escort duty, little work was left for the gunboat.

Argosy lands a successful raiding party

One exception occurred on 6 September 1863 when a party from Argosy landed at Bruinsburg, Mississippi, to destroy a ferryboat. The Northern sailors also found a small group of horsemen with a large quantity of ordnance supplies. Upon seeing the Union men, the Southerners mounted and rode away, abandoning a "... wagonload consisting of 250,000 waterproof percussion caps, 1 box containing 5,000 friction pruners .." and a few other items.

Confederate ram Webb attempts an escape down the river

The end of the war found Argosy serving in the 1st District of the Mississippi Squadron which was responsible for the river between New Orleans, Louisiana, and Donaldsonville, Louisiana. 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. False rumors – that President Jefferson Davis and other high officials of the collapsed Confederacy were on board the Southern steamer – heightened interest in her race toward freedom. Her success depended upon the steamer's slipping by Union warships without being identified. 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.

As a result, he ran Webb on a riverbank, set her afire, ordered his crew to scatter, and attempted to slip away ashore.