The first seagoing ironclad was the USS Monitor, and its profile has made it one of the most easily recognised warships of all time. Following her inconclusive battle with the Confederate ironclad Virginia the production of Union monitors was accelerated. By the end of the year a powerful squadron of monitor vessels protected the blockading squadrons off the Southern coastline, and were able to challenge Confederate control of her ports and estuaries. Further technological advancements were included in subsequent monitor designs, and by the end of the war the US Navy possessed an powerful modern coastal fleet, carrying the most powerful artillery afloat. This book covers the design, development and operational history of the Union's Monitor fleet.