London Protocol (1852)

This international treaty was the revision of an earlier protocol, which had been ratified on 2 August 1850, by the major German powers of Austria and Prussia.

The second London Protocol was recognised by the five major European powers—Austria, France, Prussia, Russia, and the United Kingdom—as well as by the Baltic Sea powers of Denmark and Sweden.

[citation needed] In 1851, the Russian emperor Nicholas I had recommended that Prince Christian of Schleswig-Holstein-Sonderburg-Glücksburg (born 1818) should be advanced in the Danish succession, and this proposal was confirmed by the London Protocol on 8 May 1852, when Prince Christian was chosen to follow Frederick VII's aging uncle Ferdinand in the line of succession.

A justification for this choice was Christian's marriage in 1842 to Louise of Hesse-Kassel, who was a daughter of the closest female relative of Frederick VII.

[1] The major powers primarily wanted to ensure, by guaranteeing Denmark's territorial integrity, that the strategically significant port of Kiel would not fall into Prussian hands.