The Cisrhenian Republic was a French client republic created on 28 August 1797 on the western bank of the Rhine river, under French domination.
Under the terms of the Peace of Basel in 1795, the Kingdom of Prussia had been compelled to cede all her territories west of the Rhine, and together with the west-Rhenish territories of the Prince-Bishops of Trier, Mainz and Cologne, the Electorate of the Palatinate, the duchies of Jülich and Cleves, and the free city of Aachen they were combined into the short-lived Cisrhenian Republic under the rule of a "Protector" Louis Lazare Hoche, a French general.
In the Treaty of Campo Formio on 18 October 1797, administration of the region was assigned to France, but it was not officially annexed until 23 September 1802. In 1798 the territory was organized by French Commissioner François Joseph Rudler into the départements of Roer, Rhin-et-Moselle, Sarre and Mont-Tonnerre. The inclusion of the western bank of the Rhine into the French Empire also led to the Reichsdeputationshauptschluss.