Alsace–Lorraine, now called Alsace–Moselle, is a historical region located in modern day France. It was created in 1871 by the German Empire after it had seized the region from the Second French Empire in the Franco-Prussian War with the Treaty of Frankfurt. Alsace–Lorraine reverted to French ownership in 1918 as part of the Treaty of Versailles and Germany's defeat in World War I.

When created in 1871, the region was named the Imperial Territory of Alsace–Lorraine (German: Reichsland Elsaß–Lothringen or Elsass–Lothringen; Alsatian: 's Richslànd Elsàss–Lothrìnga; Moselle Franconian/Luxembourgish: D'Räichland Elsass–Loutrengen) and as a new territory of the German Empire. The Empire annexed most of Alsace and the Moselle department of Lorraine, following its victory in the Franco-Prussian War. The Alsatian part lay in the Rhine Valley on the west bank of the Rhine River, east of the Vosges Mountains; the section originally in Lorraine was in the upper Moselle valley to the north of the Vosges.

The territory encompassed almost all of Alsace (93%) and over a quarter of Lorraine (26%), while the rest of these regions remained parts of France. For historical reasons, specific legal dispositions are still applied in the territory in the form of a "local law in Alsace–Moselle". In relation to its special legal status, since reversion to France, the territory has been referred to administratively as Alsace–Moselle (Alsatian: 's Elsàss–Mosel).

Since 2016, the historical territory has been part of the French administrative region of Grand Est.