After the death of the last member of this family's Hechingen branch, the remaining Catholic branch of this family dropped the suffix "Sigmaringen."
A castle formerly belonging to this family served as the seat of the government of Vichy France after the conquest of France by the Allies. A member of this family named Charles married the niece of Joachim Murat, Marie Antoinette Murat, and abdicated his position during the revolutions of 1848 in favor of his son. That son served several years as Minister-President during the regency of Wilhelm I and was named Charles Anton. A member of this family won military fame for his leadership of the army at the Siege of Plevna and won independence for his country from the Ottoman Empire at the Congress of Berlin. Another member of this family, a son of Charles Anton (*) named Leopold, became the indirect cause of the Franco-Prussian War when he was offered the Spanish throne, an offer known as this house's namesake candidacy. After the death of the last member of this family's Hechingen branch, the remaining Catholic branch of this family dropped the suffix "Sigmaringen." For 10 points, identify this family with origins in Swabia whose scion Carol I became the first king of Romania.
A castle formerly belonging to this family served as the seat of the government of Vichy France after the conquest of France by the Allies.
House of Hohenzollern [or Hohenzollern-Sigmaringen; prompt on "Sigmaringen" until mentioned]