He received no command during the Franco-Prussian War in 1870, because of his high age. He was nevertheless accused to have a part of responsibility in French defeat for having neglected to prepare for it during his second ministry and for having dissuaded Napoleon III of acting in favour of Austria at the time of the Battle of Sadova in 1866. Modern research has shown that the latter accusation is unfounded and that, quite contrarily, Randon had advocated an immediate action against Prussia.