The Merrimack was in the Gosport Navy Yard at Portsmouth, Virginia when the war broke out. It had been scheduled for repairs, but congress denied the funds, leaving her there in port. The Confederates sank lightboats between Craney Island and Sewell’s Point, which blocked the channel away from the port on April 16, 1861. On April 17, Virginia seceded and the Federal officers were ordered to remove all ships from the port.
Engineer in Chief Isherwood managed to get Merrimack’s engines lit, but could not get her out of the harbor, so he scuttled her. She burned to the water line and sank.
The Confederates took possession of a fully provisioned harbor and salvaged the Merrimack (also known as the Merrimac). She was rebuilt as the ironclad CSS Virginia. The decision to resurrect her as an ironclad was in response to reports in northern newspapers talking about construction of an ironclad to go against the southern navy.
It’s remarkable to note here how much information was freely posted in newspapers. Civil War spy Frank Stringfellow spent moths cutting out troop movements from newspapers and sending them south.
The Virginia still had workmen aboard when she sailed into her first battle at Hampton Roads on March 8, 1862 where she rammed and sank the USS Cumberland. On March 9, the Monitor arrived after nearly foundering twice. She was sent to fight the rebel monster though still unfinished in an effort to safe the Union blockade fleet.
The two ironclads fought to a standstill with neither declaring a victory, though history will give it to the Monitor since the blockade remained unbroken. The ironclads broke off and sailed away.
On May 11, 1862 the Confederates destroyed the Virginia rather than let her fall into Federal hands. Federals occupied Norfolk and the Virginia was no longer seaworthy due to the modifications turning her into an ironclad. Knowing it would be too dangerous to take her into the Atlantic, they decided to blow her up themselves.
The Monitor was lost on December 31, 1862 in high seas.
However, naval warfare was forever changed due to two squat little ironclads.