The Prince-Bishopric of Speyer, formerly known as Spires in English, was an ecclesiastical principality in what are today the German states of Rhineland-Palatinate and Baden-Württemberg. It was secularized in 1803. The prince-bishop resided in Speyer, a Free Imperial City, until the 14th century, when he moved his residence to Uddenheim (Philippsburg), then in 1723 to Bruchsal. There was a tense relationship between successive prince-bishops, who were Roman Catholic, and the civic authorities of the Free City, officially Protestant since the Reformation. The prince-provostry of Wissemburg in Alsace was ruled by the prince-bishop of Speyer in a personal union.

German mediatisation was the major redistribution and reshaping of territorial holdings that took place between 1802 and 1814 in Germany by means of the subsumption and secularisation of a large number of Imperial Estates, prefiguring, precipitating, and continuing after the dissolution of the Holy Roman Empire. Most ecclesiastical principalities, free imperial cities, secular principalities, and other minor self-ruling entities of the Holy Roman Empire lost their independent status and were absorbed by the remaining states. By the end of the mediatisation process, the number of German states had been reduced from almost 300 to just 39.