In 1792, as a result of the French Revolution and the seizure of power by Napoleon, French troops once again invaded the territories west of the Rhine and annexed them during the French period. After the defeat of Napoleon at Waterloo in 1815, most of the Hunsrück was reallocated at the Congress of Vienna to Prussia's Rhine Province. Parts of today's Birkenfeld and the northern Saarland belonged to the Oldenburg Principality of Birkenfeld until 1937.