The division reflected an adherence to the old
Frankish custom of
partible or divisible inheritance amongst a ruler's sons, rather than
primogeniture (i.e., inheritance by the eldest son) which would soon be adopted by both Frankish kingdoms. Since Lotharingia combined lengthy and vulnerable land borders with poor internal communications as it was severed by the
Alps, it was not a viable entity and soon fragmented. This made it difficult for a single ruler to reassemble Charlemagne's empire. Only
Charles the Fat achieved this briefly. In 855, the northern section became fragile Lotharingia, which became
disputed by the more powerful states that evolved out of Francia Occidentalis (present day
France) and Francia Orientalis (present day
Germany). Generations of kings of France and Germany were unable to establish a firm rule over Lothair's kingdom. While the
north of Lotharingia was then composed of
independent countries, the
southern third of Lotharingia,
Alsace-Lorraine, was traded back and forth between
France and
Germany from the 18th to the 20th century. In 1766, it passed to France after the death of
Stanisław Leszczyński, who had acquired the region from the German
Habsburgs by the
Treaty of Vienna (1738) ending the
War of Polish Succession (1733–1738). In 1871, Alsace-Lorraine became German, after the victory of
Prussia and its German allies over the French in the
Franco-Prussian War (1870–1871). In 1919, it became French again by the
Treaty of Versailles (1919), following the French victory over the Germans in
World War I (1914–1918). In 1940, Germany re-annexed Alsace-Lorraine following Germany's
conquest of France. Finally, in 1945, after
World War II (1939–1945), Alsace-Lorraine was solidified as French territory, which it remains to this day, more than a thousand years after the Treaty of Verdun. The collapse of the
Middle Frankish Kingdom also compounded the disunity of the Italian Peninsula, which persisted into the 19th century. ==See also==