1st » American Civil War: The Union Army completes its capture of New Orleans.
5th » Cinco de Mayo: troops led by Ignacio Zaragoza halt a French invasion in the Battle of Puebla in Mexico.
11th » American Civil War: The ironclad Ship CSS Virginia is scuttled in the James River (Virginia) James River northwest of Norfolk, Virginia.
12th » United States named U.S. federal troops occupy Baton Rouge, Louisiana.
13th » The USS Planter 1862 6, a steamer and gunship, steals through Confederate lines and is passed to the Union, by a southern slave, Robert Smalls, who later was officially appointed as captain, becoming the first black man to command a United States ship.
15th » President of the United States known as President Abraham Lincoln signs a bill into law creating the United States Bureau of Agriculture. It is later renamed the United States Department of Agriculture.
20th » President of the United States e.g U.S. President Abraham Lincoln signs the Homestead Act into law.
31st » American Civil War Peninsula Campaign: Battle of Seven Pines or (Battle of Fair Oaks) Confederate forces under Joseph E. Johnston & Gustavus Woodson Smith e.g G.W. Smith engage Union forces under George B. McClellan outside Richmond, Virginia.