Alsace (French: Alsace [alzas]; Alsatian: Elsàss [ˈɛlsɑs]; German: Elsass, pre-1996: Elsaß, IPA: [ˈɛlzas]; Latin: Alsatia) is the fifth-smallest of the 27 regions of France in land area (8,280 km²), and the smallest in metropolitan France. It is also the seventh-most densely populated region in France and third most densely populated region in metropolitan France, with ca. 220 inhabitants per km² (total population in 2006: 1,815,488; 1 January 2008 estimate: 1,836,000). Alsace is located on France's eastern border and on the west bank of the upper Rhine adjacent to Germany and Switzerland. The political, economic and cultural capital as well as largest city of Alsace is Strasbourg. Because that city is the seat of dozens of international organizations and bodies, Alsace is politically one of the most important regions in the European Union.

The name "Alsace" can be traced back to the Old High German Ali-saz or Elisaz, meaning "foreign domain". An alternative explanation derives it from a Germanic Ell-sass, meaning "seated on the Ill", a river in Alsace. The region was historically part of the Holy Roman Empire. It was gradually annexed by France in the 17th century under kings Louis XIII and Louis XIV and made one of the provinces of France. Alsace is frequently mentioned in conjunction with Lorraine, because German possession of parts of these two régions (as the imperial province Alsace-Lorraine, 1871–1918) was contested in the 19th and 20th centuries, during which Alsace changed hands four times between France and Germany in 75 years.

Moselle (French pronunciation: [mɔ.zɛl]) is a department in the east of France named after the river Moselle.

Moselle is one of the original 83 departments created during the French Revolution on March 4, 1790. It was created from the former province of Lorraine.

In 1793, the foreign enclaves of Manderen, Lixing-lès-Rouhling, Momerstroff, and Créhange (Kriechingen), all possessions of princes of the German Holy Roman Empire, were annexed by France and incorporated into the Moselle département.

By the Treaty of Paris of 1814 following the first defeat and abdication of Napoleon, France had to surrender almost all its conquests since 1792. On the northeastern border, France was not restored to its 1792 borders, but a new border was established to put an end to the convoluted nature of the border, with all its enclaves and exclaves. As a result, the French exclave of Tholey (now in Saarland, Germany) as well as a few communes near Sierck-les-Bains (both territories until then part of the Moselle département) were ceded to Austria. On the other hand, the French annexations of 1793 were confirmed, and furthermore, the south of the Napoleonic département of Sarre was ceded to France, including the town of Lebach, the city of Saarbrücken, and the rich coal basin nearby. France was thus a net beneficiary of the Treaty of Paris, all the new territories ceded to her being far larger and more strategic than the few territories ceded to Austria. All these new territories were incorporated into the Moselle department, and so Moselle had now a larger territory than ever since 1790.