Siege of Breda (1637) when word came that the Dutch had suddenly invested the city of Breda with a besieging army of 18,000. Breda was the capital city of the baronial fief that had once been the crown jewel in the Dutch estates of the Nassau family in the Habsburg Netherlands before the war started. Frederick Henry had therefore a personal interest in recapturing the city and its surroundings. The siege was preceded by an attempt to surprise the garrison on 21 July 1637 by Dutch cavalry under Henry Casimir I of Nassau-Dietz. However, the gates were closed in time and the Dutch skirmishers
Breda heiress of his line, Johanna of Polanen (1392–1445), married Engelbert I of Nassau (1370–1442; his sarcophagus is in the Grote Kerk in Breda). Through her, the city came into the possession of the House of Nassau, where it remained until 1795, passing to William I of Orange (1533–1584), stadtholder of Holland, Zeeland, and Utrecht and leader of the Dutch revolt. Thus, the baron of Breda was also Count of Nassau in the Holy Roman Empire, Prince of Orange, and stadtholder of the Dutch Republic (from 1572–1650, 1672–1702, 1747–1795). Breda remained part of the barony of Breda until it was captured