The administrative district of Territoire de Belfort was created under the terms of the 1871
Treaty of Frankfurt. The
German Empire annexed almost all of Alsace. Still, the French were able to negotiate the retention of the Territoire de Belfort, which was thereby separated from the rest of Alsace (where it had been part of the department of
Haut-Rhin). There were three principal reasons for this exceptional treatment: • The population in and around
Belfort was French-speaking. • Belfort had demonstrated heroic resistance under
Colonel Pierre Denfert-Rochereau against the German invasion. Belfort's
left-wing Catholic Deputy Émile Keller now conducted a similarly forceful political campaign in the
National Assembly. He argued that ceding heroic Belfort to Germany after the war would be unthinkable. • Since Belfort is situated in a relatively flat passage between the Vosges and Jura mountain ranges (known as the
Belfort Gap), the Germans agreed to leave the city in France, as Prussian military officers indicated that this strategy would give Germany a more defensible border. After retaining its unique status as a for just over half a century, Belfort was officially recognized as France's 90th department in 1922. France had recovered
Alsace three years earlier, but the decision was made not to reintegrate Belfort into
its former department. There was talk of giving it a new departmental name, with suggestions that included "
Savoureuse" (after the main river of the new department) or "
Mont-Terrible" (the name of a former
Napoleonic department embracing parts of
Switzerland). Still, there was no consensus for a name change, and the department continues to be known as the Territoire de Belfort. Belfort lies on the ridge that divides When the
regions of France were created, Belfort was not included in the region of Alsace, but the adjacent region of
Franche-Comté, since January 2016,
Bourgogne-Franche-Comté. ==Geography==