Joining Flag Officer Andrew Hull Foote's Western Gunboat Flotilla in river patrol duty, Pittsburgh attacked Fort Donelson February 14, 1862, and was damaged by counter-fire.

This daring feat made it possible for her and Carondelet to demolish batteries below New Madrid, Missouri that same day, clearing the way for the Army to cross the Mississippi River.

Pittsburgh gave continued service in the lengthy series of operations which wrested control of the lower Mississippi from the Confederacy.

The strong Confederate river fortress surrendered July 4, allowing President Abraham Lincoln at last to report, "The Father of Waters flows unvexed to the sea."

Patrol and bombardment missions on the Mississippi were interrupted the following year when Pittsburgh joined in the Red River Expedition from March to May 1864.