a political principle advanced by the French diplomat Talleyrand at the Congress of Vienna in 1814–15 to justify and defend the territorial interests of France and, in particular, to preserve the borders existing on Jan. 1, 1792, and prevent Prussian expansion.

According to the principle of legitimism, no one has the right to dispose of a crown or territory until its legitimate owner has formally relinquished his right to it. The possessions taken away from their “legal” sovereign must be returned to him. According to Talleyrand, Europe needed to banish forever any possibility of acquiring the right to a territory by a sheer conquest and to restore the sacred principle of legitimism, which ensures order and stability. The principle of legitimism was not adopted by the Congress of Vienna because it contradicted the annexation plans of tsarist Russia and of Prussia.

The term “legitimism” is also used in another sense: the loyalty to the “legal” (legitimate) dynasty of the Bourbons in France. This term arose after the July Revolution of 1830, which brought Louis Philippe of Orléans to the French throne. In a more general sense, any supporter of an overthrown monarchy is called a legitimist.