Sébastien, Duke of Penthièvre

Sebastien de Luxembourg, viscomte de Martigues (1530-1569) was a French military officer, peer of France and governor of Brittany. Martigues began his political career serving under his uncle Étampes the governor of Brittany as the lieutenant-general of the province. He gained the office of colonel-general of the French infantry after the prior office holder died at the siege of Rouen during the first war of religion. In this important military role he played a key part in the royal victory at the Battle of Dreux, the main battle of the first of the French Wars of Religion. In 1565 on the death of his uncle, he gained both the governorship of Brittany and the county of Penthièvre which was subsequently elevated to a dukedom.