In 1798, Thurgau was occupied by French troops, along with much of the rest of Switzerland. The adoption of the Swiss constitution ended Arbon's dependence on the Bishops of Constance. The Bishop's representative, Franz Xaver Wirz von Rudenz, was forced to leave the city. In 1803, Arbon became part of the new canton of Thurgau. From 1803 to 1815, Arbon and Horn (an exclave in the canton of St. Gallen) were united in one municipality.