I am aware that they are not properly seagoing craft, that they are very slow, work heavily against a current or tide, are liable to founder, and the like, but . . .” Thus did Massachusetts Governor John A. Andrew beg U.S. Secretary of the Navy Gideon Welles in a 4 May 1863 letter—for a second time—to have one of the six new monitors, then under construction in Boston, assigned to protect its harbor.
The ships were part of a 20-ship class of very shallow draft ironclads designed for the waters of Southern rivers and estuaries and the Western waterways. They were fostered by Assistant Secretary of the Navy Gustavus Vasa Fox, who believed a monitor with a six-foot draft was the answer to combating Confederates in their own domain. In August 1862, Fox asked John Ericsson, the prototype Monitor’s designer, to take on the project. Ericsson responded in October with estimates and sketches for a single-turret, two-gun monitor with a 221-foot-long, 41-foot beam hull.