He negotiates all treaties or alliances with foreign states, protects British subjects residing abroad, and demands satisfaction for any injuries they may sustain at the hands of foreigners.
Mediation may also take place after war has broken out, with a view to putting an end to it on terms. In either case the mediating power negotiates on behalf of the parties who invoke or accept its aid, but does not go farther.
The Roman Catholic Church, even when recognized as the state religion, is nowhere "established" in the sense of being identified with the state, but is rather an imperium in imperio which negotiates on equal terms with the state, the results being embodied in concordats (q.v.) between the state and the pope as head of the Church.