John Ericsson Memorial in Washington DC
Designer of the ironclad Monitor
Ericsson's chief fame is for his design of the USS Monitor, an armored ship that was designed in direct response to the Confederate craft the CSS Virginia (formerly the USA ship USS Merrimac), which had nearly single-handedly defeated the Union navy blockade at Hampton Roads, Virginia.
Left unchecked, the potential for the CSS Virginia (and other Confederate craft built like her) was that it could annihilate the Union Navy entirely. John Ericsson's design work was the principal element that checked the CSS Virginia, and this in turn magnified the ability of the Union to overcome the Southern Confederacy.
Washington DC from the Wilson Bridge
Original photos and page 2007