The court-martial of Fitz John Porter was a major event of the American Civil War. Major General Fitz John Porter was found guilty of disobeying a lawful order and misconduct in front of the enemy, and was removed from command based on internal political machinations of the Union Army. The court-martial was later found to be unjust and overturned, and Porter was reinstated in the United States Army.

Fitz John Porter was a career United States Army officer and a Union general during the American Civil War. He is most known for his performance at the Second Battle of Bull Run and his subsequent court martial.