As the American Civil War entered its first winter, Union naval forces on western rivers worked to establish the dominance that would eventually let federal gunboats and ironclads split the Confederacy along the Mississippi. Control of these waterways, achieved gradually over 1861 and 1862, proved decisive in the eventual Union strategy of dividing and strangling the South.
The Mississippi River and its tributaries formed the circulatory system of the western Confederacy, carrying troops, cotton, and supplies between Texas, Arkansas, and the eastern rebel states. Union strategists, including the otherwise underappreciated Winfield Scott with his 'Anaconda Plan,' recognized early that severing this artery would be as important as any battlefield victory in the east.
The autumn and winter of 1861 saw the construction and deployment of a new kind of weapon: ironclad gunboats, ungainly armored vessels built at breakneck speed in yards along the Ohio River, designed specifically for the shallow, muddy conditions of western rivers rather than the open ocean.
These vessels, and the campaigns they supported, set the stage for the fall of Forts Henry and Donelson in early 1862 and eventually the capture of Vicksburg in 1863, achievements that cut the Confederacy in two and are considered among the most strategically important Union successes of the entire war.