The Treaty of Meerssen in 870 was an agreement of the division of the Carolingian Empire by the surviving sons of Louis I, Charles II of the West Franks and Louis the German of East Franks, signed at the town of Meerssen, which is now in the Netherlands. Louis II, Holy Roman Emperor, with the support of Pope Hadrian II sought a piece of the partition, but was denied. 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 Lothar II, King of Lotharingia. The north of Lotharingia was in Danish Viking control and was only divided between West Francia and East Francia on paper.