Like many churchmen of his day, de Sourdis was a military man as well as a prelate. He fought in the Thirty Years' War and in 1628 served as commander of the artillery at the Siege of La Rochelle. The next year, 1629, Henri succeeded his brother François de Sourdis as Archbishop of Bordeaux. The succession had been legally arranged several years before and was confirmed by Cardinal Richelieu the day François died. In 1640, de Sourdis was moved to command in the Mediterranean, but found few opportunities for battle because of the uncertain neutrality of the Republic of Genoa.