The Treaty of Mersen (870) was an agreement of the division of the Carolingian Empire by the sons of Louis I, Charles II of the West Franks (France) and Louis the German of East Franks (Germany), signed at Mersen, which is now in the Netherlands. The treaty replaced the Treaty of Verdun. The Kingdom of Lotharingia was divided between Charles II and Louis the German, in 869, after the death of their nephew Lothair, King of Lotharingia.
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