The legal basis for mediatisation was the Reichsdeputationshauptschluss of 1803, which had become necessary under pressure from France. The Treaty of the Confederation of the Rhine of 1806 continued the process of mediatisation. The constitution of the German Confederation of 1815 confirmed the mediatisation, but preserved certain rights for the mediatised princes within their former realms, now ranked as state countries, such as first instance jurisdiction, supervision of religion and foundations.