In 1866 fought as division commander in the Third Italian War of Independence. In the wake of the defeat at Custoza, he was stripped of his command after a clash with Alfonso La Marmora, the Italian chief of staff (today generally considered the main responsible of the defeat). Sirtori renounced to all his army decorations and wages. His removal led some of his enemies to accuse him of the defeat: the polemics went on until 1871, when another general, Giuseppe Govone, now turned Ministry of War, re-established Sirtori's honor, naming him commander of a division in Alessandria.