On 9 March 1862 the world's first battle between two ironclad warships took place in the confined waters of Hampton Roads, Virginia. The previous day the Confederate ironclad CSS Virginia, impervious to her enemy's guns, had sunk two Union warships. When she re-emerged from Norfolk to complete the destruction of the Union blockading squadron the USS Monitor steamed out to meet her. The four-hour duel that ensued was a stalemate, but crucially the Virginia had failed to break the Northern blockade of the Southern ports. Nevertheless, in a single battle these two vessels rendered wooden warships obsolete and transformed the face of naval warfare forever.