The Rhine-and-Lahn duchy assembled in 1806 when Napoleon raised the surviving Walramian counts of Nassau-Usingen and Nassau-Weilburg to dukes inside the Confederation of the Rhine; united under a single duke in 1816, ruled from Wiesbaden rather than from Nassau itself.
Duke Adolph backed Austria in 1866; Prussian troops overran the duchy and it was formally incorporated into Prussia on 3 October 1866, becoming part of the Province of Hesse-Nassau. Adolph inherited the Grand Duchy of Luxembourg in 1890.
Polity-specific study of exactly the Napoleonic settlement that created the duchy in 1806.
Context for the Nassau counties inside the Empire before their 1806 promotion.