Complex sentence: The Congress of Vienna instituted a territorial exchange between Hanover and Prussia, in which Hanover increased its area substantially, gaining the Bishopric of Hildesheim, East Frisia, the Lower County of Lingen and the northern part of the Bishopric of Münster.
Split into simpler sentences: The Congress of Vienna installed a territorial exchange between Hanover and Prussia, in which Hanover increased its area substantially. Hanover gained the Bishopric of Hildesheim, East Frisia, the Lower County of Lingen and the northern part of the Bishopric of Münster.