As the ram fleet and western flotilla prepared to attack, General Henry Wager Halleck's capture of Corinth, Mississippi on 30 May, cut the railway lines which supported the Confederate positions at Forts Pillow and Randolph forcing the South to abandon these river strongholds.

At this point Colonel Ellet ordered his rams to steam through the line of Flag Officer Davis' slower ironclads and run down the Confederate steamers.

Farragut ran the gauntlet past Vicksburg's guns 28 June, and Flag Officer Davis joined him above the city with the western flotilla 1 July.

On 15 July Confederate ironclad ram Arkansas raced down the Yazoo River and fought through the combined Union squadrons to shelter under the guns at Vicksburg.

At the first sight of Arkansas, Lancaster cut her line; dropped down with the current; and strained to build up sufficient steam pressure to ram the southern ship.

As her speed increased, Lancaster headed straight for Arkansas; but when she was a mere 100 yards from her quarry, a broadside from the ironclad opened up her steam lines and made her unmanageable.

This vital task of protecting General Ulysses S. Grant's logistic lines was necessitated by stepped-up southern guerrilla activity and cavalry raids along the river banks.

As the muddy Mississippi poured into her hull, Lancaster's commander, Lieutenant Colonel John A. Ellet, ordered her crew to abandon the ship, and the ram sank hard by the bow.