From 1381 to 1793 the counts of Nassau-Saarbrücken were the main local rulers. In 1549, Emperor Charles V prompted the construction of the "Alte Brücke" (old bridge) connecting Saarbrücken and St Johann. At the beginning of the 17th century, Count Ludwig II ordered the construction of a new Renaissance-style castle on the site of the old castle, and founded Saarbrücken's oldest secondary school, the "Ludwigsgymnasium". During the Thirty Years' War, the population of Saarbrücken was reduced to just 70 by 1637, down from 4500 in 1628. During the Franco-Dutch War, King Louis XIV's troops burned down Saarbrücken in 1677, almost completely destroying the city such that just 8 houses remained standing. The area was incorporated into France for the first time in the 1680s. In 1697 France was forced to relinquish the Saar province, but from 1793 to 1815 regained control of the region.