The new ram joined Rear Admiral David Dixon Porter's Mississippi Squadron above Vicksburg in time for the famous dash on 16 April 1863 past the deadly batteries which protected the vital Confederate fortress.

The successful steaming of the squadron past the heavy batteries contributed to the early seizure of Grand Gulf, the eventual fall of Vicksburg itself, and ultimately the conquest of the entire Mississippi River.

Though Benton, Tuscumbia, and Pittsburgh were "pretty much cut up" in the engagement, the expedition was successful, and the net result was summed up by Porter, "We are now in a position to make a landing where the general [Grant] pleases."

On 3 May Porter once again moved his gunboats against the Confederate batteries, but the southerners, finding their position totally untenable after Grant had taken his army into the country back of Grand Gulf, had evacuated.

Subsequently, turning the town over to Army troops and unable to continue upriver because of the low water, Porter's force returned to Fort DeRussy and partially destroyed it.

Eastport led the way on 12 March 1864, followed by ironclads Essex, Ozark, Osage and Neosho, and wooden steamers Lafayette, Choctaw, Fort Hindman, and Cricket.

When they reached the obstructions which the southerners had taken five months to build below Fort DeRussy, "...our energetic sailors," Porter observed, "with hard work opened a passage in a few hours."

The Union ships reached Alexandria the next morning and a landing party occupied the town and awaited the arrival of Major General Nathaniel Prentiss Banks' army, delayed by heavy rains.

At Grand Encore he left the heavier gunboats behind, including Lafayette, and continued up stream 7 April with three ironclads and three wooden steamers to meet General Banks at Shreveport, Louisiana.

Before this formidable obstruction could be removed, word arrived that General Banks had been decisively defeated in the Battle of Sabine Cross Roads near Grand Encore and was in headlong retreat.

Falling water and increasing Confederate fire from the riverbank strained the seamanship and ingenuity of the Union sailors in their desperate struggle to avoid being trapped above the Alexandria Rapids.