The Siege of Aachen took place in late August, 1614, when the Spanish Army of Flanders, led by Ambrogio Spinola, 1st Marquis of the Balbases, marched from Maastricht to Germany to support Wolfgang Wilhelm, Count Palatine of Neuburg, during the War of the Jülich Succession. Despite its status as a free imperial city, Aachen was under the protection of John Sigismund of Brandenburg, Neunburg's ally, and then rival, in the battle for the United Duchies of Jülich-Cleves-Berg. In 1611, the Protestant population of Aachen revolted against the Catholic city council, and seized the power. When the Holy Roman Emperor Rudolf II, observing the Peace of Augsburg, ordered the previous state to be restored, the Protestants allied themselves with the Margraviate of Brandenburg. The unexpected arrival of