1) On March 31, 1661, Charles County was officially formed in Maryland. Named after King Charles I of England, the county was established by a decree from the Maryland General Assembly.

2) In 1774, the Maryland State Convention gathered in Annapolis and voted to support the Continental Association, which called for a boycott of British goods in response to the passage of the Intolerable Acts.

3) On March 31, 1813, the USS Constellation engaged in battle with the British warship HMS Java off the coast of Brazil, ultimately capturing the Java and earning the nickname "Yankee Racehorse."

4) The Baltimore and Ohio Railroad Company was granted a charter by the Maryland General Assembly on March 31, 1827, paving the way for the construction of the nation's first commercial railroad.

5) In 1863, the Union army under General John Sedgwick attacked Confederate forces at the Battle of Manassas Gap, a minor engagement in the larger Civil War campaign in Virginia. Maryland troops played a significant role in the Union victory.