He is remembered for mortally injuring Henry II in a jousting accident and subsequently converting to Protestantism, the faith that the Scots Guard sought to suppress.

Shortly after Condé's death at Jarnac in March 1569, Montgomery was tasked with restoring Jeanne d'Albret, the Huguenot queen of Navarre, to her territories in Béarn, which had been conquered by Catholic forces.

The combined army, led by Coligny and the young princes of Condé and Navarre, fought the Catholics to a standstill at Arnay-le-Duc and imposed a favorable peace on the Crown.

On 26 June 1574, as he was about to be beheaded,[1] Montgomery was informed that a royal edict had proclaimed that his property would be confiscated and his children deprived of their titles.

A freely adapted version of Montgomery's life is told in Alexandre Dumas' novel The Two Dianas (1846–47), and he appears as a central character in Johann August Apel's story "Klara Mongomery" in the Gespensterbuch (1811).