His successors to the office of President of the U.S. tended to be hard on the hapless Franklin Pierce. Teddy Roosevelt called him a "servile tool of men worse than himself." Harry Truman called him a nincompoop. Ulysses S. Grant was kinder in his assessment of Pierce. Grant wrote in his memoirs:
General Franklin Pierce had joined the army in Mexico, at Puebla, a short time before the advance upon the capital commenced. He had consequently not been in any of the engagements of the war up to the battle of Contreras. By an unfortunate fall of his horse on the afternoon of the 19th he was painfully injured. The next day, when his brigade, with the other troops engaged on the same field, was ordered against the flank and rear of the enemy guarding the different points of the road from San Augustin Tlalpam to the city, General Pierce attempted to accompany them. He was not sufficiently recovered to do so, and fainted. This circumstance gave rise to exceedingly unfair and unjust criticisms of him when he became a candidate for the Presidency. Whatever General Pierce’s qualifications may have been for the Presidency, he was a gentleman and a man of courage. I was not a supporter of him politically, but I knew him more intimately than I did any other of the volunteer generals.Maybe Grant was more sympathetic because he shared Pierce's weakness for alcohol.