- May 1 Edward D. Tracy, American Brigadier General (Confederate Army), dies in battle at 29
- May 3 Elisha Franklin Paxton [Bull Paxton], American general (Confederate Army), dies leading Stoneville Brigade at the Battle of Chancellorsville at 35
- May 7 Amiel Weeks Whipple, US Union gen-major, dies of injuries at 46
Stonewall Jackson (1824-1863)
May 10 Confederate general during the American Civil War, dies of pneumonia at 39
- May 14 Emile Prudent, French pianist and composer, dies at 46
- May 16 Lloyd Tilghman, Confederate brigadier general, dies in battle at 47
- May 27 Edward Payson Chapin, American lawyer and Union Army Colonel (posthumously elevated to Brigadier General), dies of injuries from the Siege of Port Hudson, Louisiana at 31
- May 28 Edmund Kirby Jr, American Brigadier General (Union Army), dies of injuries at 23
Assassination
Car Crash
Hanging
Killed in Action
Plane Crash
Poisoning