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 under general Alexander Farnese, Duke of Parma (Siege of Maastricht, 1579). For over fifty years the Spanish crown took over the role of the dukes of Brabant in the joint sovereignty over Maastricht. In 1632 the city was conquered by Frederick Henry, Prince of Orange and the Dutch States General replaced the Spanish crown in the joint government of Maastricht.