- Mar 3 Union forces under General Pope lay siege to New Madrid, Missouri (US Civil War)
- Mar 5 Union troops under Brigadier General Wright occupy Fernandina, Florida (US Civil War)
- Mar 6 Battle of Pea Ridge, Arkansas (Elkhorn Tavern)
- Mar 7 Battle of Elkhorn Tavern, Day 2, Generals Ben McCulloch & James McIntosh killed
- Mar 8 Battle of Elkhorn Tavern ends with Confederate withdrawal
- Mar 8 Confederate ironclad "Merrimack" launched
- Mar 8 Naval Engagement at Hampton Roads, VA CSS Virginia, Jamestown & Yorktown vs USS Cumberland, Congress & Monitor
- Mar 9 USS Monitor and CSS Merrimack battle in Hampton Roads
- Mar 10 Great Britain & France recognise independence of Zanzibar
- Mar 10 US issues 1st paper money in the form of $5, $10, $20, $50, $100, $500 and $1000 notes
Event of Interest
Mar 11 Abraham Lincoln removes George McClellen as general-in-chief
Abraham Lincoln
Event of Interest
Mar 11 12] General Stonewall Jackson evacuates Winchester Virginia Army of the Potomac. Gen Henry Halleck is named general-in-chief
Stonewall Jackson
- Mar 14 Battle of New Bern North Carolina: General Burnside conquers New Bern
- Mar 15 General John Hunt Morgan begins 4 days of raids near Gallatin, Tennessee
- Mar 16 Battle at Pound Gap, Kentucky: Confederates separate battles
- Mar 22 San Marino & Italy conclude treaty of friendship & cooperation
- Mar 23 Battle of Kernstown Virginia, Jackson begins his Valley Campaign
- Mar 26 Battle of La Glorieta Pass, New Mexico Territory (Apache Canyon, Pigeon's Ranch)
- Mar 28 Skirmish at Bealeton Station, Virginia
- Mar 31 Civil War action at Island #10 on Mississippi River