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.

[1] The Prince-Bishopric of Speyer belonged to the Upper Rhenish Circle of the Holy Roman Empire.

One of the smallest principalities of the Holy Roman Empire, it consisted of more than half a dozen separate enclaves totalling about 28 German square miles (about 1540 km2) on both sides of the Rhine.

In the 10th and 11th centuries, the diocese received additional lands, including gifts by emperor Otto I.

From 1111 the citizens of the city of Speyer began to increasingly loosen their bonds to the rulership of the bishop.

At the beginning of the 17th century bishop Philipp Christoph von Sötern expanded the fortress of Philippsburg.

However, France annexed parts of the bishopric's left-bank territories in 1681 as Reunion and seized Philippsburg again in 1688 at the beginning of the Nine Years' War.