The important strategic location of Maastricht resulted in the construction of an impressive array of fortifications around the city during this period. The Spanish and Dutch garrisons became an important factor in the city's economy. In 1579 the city was sacked by the Spanish army led by the Duke of Parma (Siege of Maastricht, 1579). For over fifty years the Spanish crown took over the role previously held by the dukes of Brabant in the joint sovereignty over Maastricht. In 1632 the city was conquered by Prince Frederick Henry of Orange and the Dutch States General replaced the Spanish crown in the joint government of Maastricht.