London Protocol

United Kingdom-Prussia [1852]

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June 30, 2026

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The London Protocol of 1852 was an agreement between Denmark, Prussia, and Austria concerning the status of the duchies of Schleswig and Holstein. These regions had a mixed Danish and German population and a complex history of being ruled by Danish kings while Holstein was also a part of the German Confederation. The core of the dispute was whether Schleswig should be more closely tied to Denmark or Holstein, and by extension, to Germany.

The protocol aimed to maintain the integrity of the Danish realm, with Denmark agreeing not to tie Schleswig more closely to Denmark than to Holstein. However, this agreement was short-lived. In 1863, Denmark adopted a new constitution for Schleswig, leading to war with Prussia and Austria in 1864. Ultimately, Prussia and Austria annexed Schleswig and Holstein, with both eventually becoming part of Prussia after the Seven Weeks' War in 1866. The question of North Schleswig's status was later resolved by a plebiscite in 1920, with the northern part voting to join Denmark.12

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Neuchâtel crisis
Four years later, in the London Protocol of 1852, the other Great Powers formally acknowledged his rights in Neuchâtel, but with the proviso that Prussia should do nothing to assert them without their concurrence. In September 1856 there was an unsuccessful pro-Prussian coup d’etat in Neuchâtel, conducted by loyalist aristocrats…
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Four years later, in the London Protocol of 1852, the other Great Powers formally acknowledged his rights in Neuchâtel, but with the proviso that Prussia should do nothing to assert them without their concurrence. In September 1856 there was an unsuccessful pro-Prussian coup d’etat in Neuchâtel, conducted by loyalist aristocrats…
Read More

Schleswig-Holstein
History
…pressured Prussia into accepting the London Protocol of 1852. Under the terms of this peace agreement, the German Confederation returned Schleswig-Holstein to Denmark. In an agreement with Prussia under the 1852 protocol, the Danish government in return undertook not to tie Schleswig more closely to Denmark than to its sister…
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…pressured Prussia into accepting the London Protocol of 1852. Under the terms of this peace agreement, the German Confederation returned Schleswig-Holstein to Denmark. In an agreement with Prussia under the 1852 protocol, the Danish government in return undertook not to tie Schleswig more closely to Denmark than to its sister…
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