March 3rd saw the appointment of Andrew Johnson as the Military Governor of Tennessee by President Lincoln.
On that same day, the action in south Missouri continues as Union General John Pope lays siege to New Madrid.
On the 4th, faulty communications resulted in the relieving of General Grant from command by General Henry Halleck.
The Battle of Pea Ridge, also known as Elkhorn Tavern, was fought from March 6-8 in northwest Arkansas near the Missouri border. Union forces under Samuel Curtis had driven Confederates from central Missouri into northwest Arkansas. Confederate General Earl Van Dorn launched a counter-offensive but Curtis held off the attack and drove the southerners from the battlefield on the second day. It was one of the few battles in the entire war when the Confederates had a numerical superiority on the battlefield. It was a costly fight for the south. Three CSA generals were killed or mortally wounded and recent estimates put the overall loss at around 2,000 soldiers. After the battle, Van Dorn’s forces were forced to live off the land for a week. During that time, thousands of troops originally under Sterling Price deserted and returned home to Missouri. A few weeks later, the remnants of Van Dorn’s forces were transferred to Tennessee, leaving Arkansas virtually undefended.
Also on March 6th, President Lincoln proposed that slaves in border states be emancipated gradually with compensation being paid to their owners. Also on that day, the first Union ironclad ship, the USS Monitor put to sea from New York. And on the 8th the Confederate Ironclad, CSS Virginia (also known as the Merrimac) engaged and destroyed two Union frigates.
On March 8th, after intelligence reports of increased Union activity provided by JEB Stuart, Joseph E. Johnston withdrew the Confederate Army of the Potomac from Centerville, VA to the Rappahannock River. On that same day, Lincoln, frustrated at McClellan’s failure or refusal to appoint corps commanders, named Edwin Sumner, Samuel Heintzelman, Erasmus Keyes, and Irvin McDowell to those posts.
March 9th was an important date in Naval history when the two opposing ironclads, Monitor and Merrimac faced off in Hampton Roads, Virginia. The CSS Merrimac was sent to the area in an attempt to break the Union blockade that was preventing international shipments from reaching Norfolk and Richmond. The two ships fought for three hours, without a decisive victory. However since Merrimac retired to repair battle damage and the blockade remained intact, the battle was clearly a strategic victory for the Union. Neither ship would survive the year. In May, after General Benjamin Huger abandoned Norfolk without telling anybody in the Navy, the Merrimac was stranded by low tide. Her Captain had her burned. The ship’s magazine blew and destroyed the ship. The Union Monitor survived to the end of the year, when she foundered in high seas off the Virginia Capes.