Capture of Oppenheim The Capture of Oppenheim or the Spanish capture of Oppenheim took place on 14 September 1620 , at Oppenheim , Electorate of the Palatinate , between the Spanish army commanded by Don Ambrosio Spinola , Marquis of the Balbases , against the forces of the Electoral Palatinate led by Joachim Ernst , Margrave of Brandenburg - Ansbach , during the Palatinate campaign , in the context of the Thirty Years ' War . The Spanish troops under Spinola , with a great maneuver of distraction over Worms , deceived the Protestant army of Joachim Ernst , and captured the important town of Oppenheim without too much difficulty , causing a severe blow to the Protestant forces . Background . In 1620 the Spanish Monarchy entered the Thirty Years ' War with the intention of conquering the Electoral Palatinate . The Spanish saw this as necessary because the Palatinate lay on the route from Italy to the Spanish Netherlands ( the Spanish Road ) . Also , Spain was Catholic , so they naturally supported the Holy Roman Emperor against the Protestants in the Thirty Years ' War . In August 1620 , Don Ambrosio Spinola , as commander - in - chief of the Army of Flanders , invaded the Palatinate from the Spanish Netherlands and advanced over Frankfurt . The rapid relief introduced in this city by the Protestants dissuaded him from attack , and Spinola decided march to Oppenheim . In early September the towns of Bad Kreuznach and Alsheim were captured by the Spaniards . The primary objective of Spinola was to occupy a city of some entity that would allow secure their supplies and ammunition , thus anticipating the arrival of winter . The attention of the Marquis focused on Oppenheim , a town of strategic importance because their bridge guarded the entrance to the heart of the Electorate of the Palatinate . The town , however , was strongly garrisoned and was protected by strong fortifications , so an immediate assault was seen as an option inadvisable . Spinola raised his camp at Alsheim , and performed a great maneuver of distraction , simulated a march over Worms to distract the forces of the Protestant Union . Joachim Ernst , Margrave of Brandenburg - Ansbach , who commanded the Protestant army stationed in Oppenheim and surroundings , about 24 , 000 soldiers , took the bait and went with most of his troops to Worms , leaving a small garrison in Oppehneim . Spinola , between therefore , taking advantage of the night approached to Oppenheim , where he arrived with his army to dawn on 14 September , and the assault on the positions of the town not long in coming . The Protestant garrison , seeing such formidable army , forsook their defenses in a hurry , and soon surrendered without suffering more than a few killed by the assailants . According to the correspondence of Spinola , the Protestant garrison consisted of 800 strong " musketeer s " recruited in the Palatinate . Oppenheim was captured and the Protestant soldiers were disarmed and released . Besides several flags , the Spanish seized the baggage of Protestant soldiers in the barracks of the town . Consequences . The loss of Oppenheim was a severe blow to the Palatinate , as the town was a key to dominate the shore of Rhine , because their bridge , guarded the entrance to the heart of the Palatinate . The bridge had been destroyed and Spinola ordered rebuild it . Also sent to reinforce the defenses and established his ammunition dump . The various garrisons that had been left in the conquered places had driven down the number of the Spanish army , so that Spinola decided quartered in Oppenheim , and requested reinforcements to Archduke Albert in Brussels . On 25 September , there was a council of the principal officers of the Spanish army , and that day it was learned that the Protestant cavalry were preparing an attack on their barracks . Spinola dispatched to Count Hendrik van den Bergh , in command of 2 , 200 cavalry , the regiment of the Count of Henden and 3 cannons , to ambush , but the fight did not occur . At the onset of winter , the two opposing armies withdrew to their garrisons . By then , the Protestants had already received the expected reinforcements from England led by Sir Horace Vere . In the six months following , the Spaniards captured more than 30 towns and castles along the Lower Palatinate .