The gunboat flotilla that Flag Officer Andrew H. Foote launched against Forts Henry and Donelson consisted of both timberclad and ironclad vessels. The timberclads - Conestoga, Lexington, and Tyler - were commercial river steamers converted to gunboats by adding heavy wooden bulkheads and a mix of cannon. The ironclads, all named for towns on the Mississippi and Ohio rivers - Carondelet, Cincinnati, Louisville, Mound City, Pittsburg, and St. Louis - were broad-beam, shallow-draft vessels protected with 2.5 inches of armor on their sides (called casemates) and 1.25 inches on the conical forward pilothouse. They were built by James Eads, a civil engineer with riverboat experience. Because of their rectangular sloped casemates, designed by by Samuel M. Pook, made them resemble mud turtles, they were called "Pook Turtles."
Flag Officer Andrew H. Foote
Flag officer Andrew Hull Foote, a veteran of nearly 40 years of naval service, commanded the Union's Western Flotilla. Blunt and of implacable resolve, Foote, like Grant, believed the best way to defeat an enemy was to attack him.