1864

1864 (MDCCCLXIV) was a leap year starting on Friday of the Gregorian calendar and a leap year starting on Wednesday of the Julian calendar, the 1864th year of the Common Era (CE) and Anno Domini (AD) designations, the 864th year of the 2nd millennium, the 64th year of the 19th century, and the 5th year of the 1860s decade. As of the start of 1864, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.

• May 5 - American Civil War: The Battle of the Wilderness starts in Virginia.
• August 21 - American Civil War: In the Lawrence Massacre, Confederates attack the town of Lawrence, Kansas and kill 150 people.
• September 1 - The Charlottetown Conference starts.
• November 25 - The book Journey to the Center of the Earth by Jules Verne is published.

• Fort Baker is built near Las Vegas, Nevada.
• Father Damien goes to Hawaii.
• The Great Central Fair is held in June in Philadelphia.
• Ponsonby's Column is destroyed by lightning.

• January 16 - Frank Bacon, American actor
• May 5 - Nellie Bly, American journalist
• June 14 - Alois Alzheimer, German psychiatrist

• May 19 – Nathaniel Hawthorne, American writer
• December 31 - George M. Dallas, 11th Vice President of the United States