On 13 February 1829, Carl married the Bohemian Countess Maria von :de:Klebelsberg |Klebelsberg, daughter of Count Maximilian von Klebelsberg and his wife Maria Anna von Turba. They had two sons:
Prince Eduard Friedrich Maximilian Johann of Leiningen.
Minor Prince
Carl had attended a private school in Bern and from 1821 onwards studied law at the University of Göttingen with the jurist Karl Friedrich Eichhorn, then one of the principal authorities on German constitutional law and leading proponent of the German Historical School of jurisprudence. At the British court, his multifaceted interests in art were aroused. From 1828, he had Waldleiningen Castle near Mörschenhardt erected as his private residence, a Romantic complex resembling Neo-Gothic castles in Britain, such as Abbotsford House. As a mediatized house, the Princes of the Leiningen were members of the Landtag diet in Baden, as well as in Bavaria and Hesse. Prince Carl became president of the Bavarian upper house in 1842 and also pursued a career in the Bavarian Army as Lieutenant general à la suite of the Cavalry. On 20 April 1842, he and 20 other noblemen gathered at Biebrich Palace, where they established the Adelsverein to organize the settlement of German emigrants in Texas; Carl was elected president of the society.
By the German revolutions of 1848–49, Leiningen had achieved much reputation as a liberal reformer and freethinker. He advocated the implementation of parliamentarism and openly criticized aristocracy's privileges; therefore, he was appointed Prime Minister of Revolutionary Germany by Regent Archduke John of Austria on 6 August 1848. With a Catholic head of state and a Lutheran head of government, an equilibrium was reached in German dualism; moreover, Leiningen's close relations to the British Royal House were generally appreciated. His cabinet initially could rely on a liberal and left-wing majority in the newly established Frankfurt Parliament, however, as early as on 5 September, he resigned over the Schleswig-Holstein Question when in the First Schleswig War King Frederick William IV of Prussia unilaterally signed an armistice with Denmark at Malmö. The delegates of the Frankfurt assembly reacted with outrage and Leiningen, unable to assert the powers of the central authority, was forced to step down. He was succeeded by the Austrian politician Anton von Schmerling, who acted as Prime Minister until December.
In 1851, he also resigned as president of the Adelsverein and was succeeded by Prince Hermann of Wied. Shortly after his half-niece Victoria became engaged to Prince Frederick of Prussia, in 1855, he suffered a severe apoplectic attack. A second attack in November the following year was fatal, and he died at Waldleiningen Castle at the age of fifty-two, with his sister Feodora at his bedside.