Fitz John Porter

Fitz John Porter (August 31, 1822 – May 21, 1901) (sometimes written FitzJohn Porter or 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.
Although Porter served well in the early battles of the Civil War, his military career was ruined by the controversial trial, which was called by his political rivals. After the war, he worked for almost 25 years to restore his tarnished reputation and was finally restored to the army's roll.

On November 25, 1862, Porter was arrested and court-martialed for his actions at Second Bull Run. By this time, McClellan had been relieved by President Abraham Lincoln and could not provide political cover for his protégé. Porter's association with the disgraced McClellan and his open criticism of Pope were significant reasons for his conviction at court-martial. Porter was found guilty on January 10, 1863, of disobedience and misconduct, and he was dismissed from the Army on January 21, 1863.
In describing the Battle of Second Manassas, Edward Porter Alexander wrote that Confederates who knew Porter respected him greatly and considered his dismissal "one of the best fruits of their victory".

In 1878, a special commission under General John Schofield exonerated Porter by finding that his reluctance to attack Longstreet probably saved Pope's Army of Virginia from an even greater defeat. Eight years later, President Grover Cleveland commuted Porter's sentence and a special act of the U.S. Congress restored Porter's commission as an infantry colonel in the U.S. Army, backdated to May 14, 1861, but without any back pay due. Two days later, August 7, 1886, Porter, seeing vindication, voluntarily retired from the Army.
https://en.wikipedia.org/wiki/Fitz_John_Porter