She was the daughter of the emperor Charles VI. of Hapsburg, whose principal aim during a long reign seemed to be to secure to his heiress the succession to all the hereditary dominions of his house. By ample cessions of territory to various princes of Europe, he finally attained a general acknowledgment, though not by the Bourbons, of the " pragmatic sanction;" and Maria Theresa, a princess of rare beauty and talents, received not only an education fitting her future condition, but was also early initiated into the secrets of state and admitted to the council of her father. In 1736 she was married to Francis Stephen of Lorraine, afterward grand duke of Tuscany, and eventually German emperor under the name of Francis I., who was always glad to leave affairs of state to his consort, while he employed himself in profitable private speculations. Charles died Oct. 20, 1740, and at once, in spite of the pragmatic sanction, claimant after claimant raised pretensions to the whole or parts of his possessions. The young princess saw herself surrounded by enemies.
Frederick the Great of Prussia occupied Silesia; Charles Albert of Bavaria was elected emperor under the name of Charles VII.; Spain, Sardinia, and Augustus III. of Poland and Saxony threatened to enforce various claims by force of arms; and France, which had no rights of succession of its own, was ready to support those of others. George II. of England alone proved a faithful ally. At the diet of Presburg in 1641 she put herself and her infant son Joseph under the protection of the Hungarians, who promised to die for their "king" Maria Theresa; and their enthusiasm became a support powerful beyond all expectation. Frederick made peace at Bres-lau (1742), retaining Silesia, which he had conquered; but Charles VII. lost even his own dominion, Bavaria. This success of the Austrian arms, however, raised the apprehensions of Frederick, and the second Silesian war ensued (1744), France simultaneously declaring war against England. Louis XV. himself appeared on the field, and Marshal Saxe won battle after battle in the Netherlands; Frederick, too, was successful.
Saxony, however, was now the ally of Maria Theresa. Charles VII. died soon after reentering his capital Munich, and his son and successor not only renounced all his claims, but also supported the election of Maria Theresa's husband to the imperial throne of Germanv (1745). Frederick, confirmed in the possession of Silesia, made peace at Dresden (1745). The war against Spain and France was continued, Marshal Saxe being victorious at Fontenoy (1745), Raucoux (1746), and Lawfeldt (1747), while England was successful against the pretender, in the colonies, and on the seas. Elizabeth of Russia declaring for Maria Theresa, the war was terminated by the peace of Aix-la-Chapelle (1748), Austria ceding Parma, Pia-cenza, and Guastalla to Don Philip, prince of Spain, and some districts of the duchy of Milan to Sardinia. Maria Theresa now turned her principal attention to the internal affairs of her states. Following chiefly the advice of her minister Kaunitz, she introduced numerous reforms, organized the administration, alleviated the burdens of the peasantry, abolished torture, created various institutions of learning, promoted industry and trade, and, though a zealous Catholic herself, subjected the papal bulls to the placet regium.
In regard to Hungary, she observed a mild but slowly denationalizing policy. The external diplomacy of Kaunitz was also active, and when he finally succeeded in gaining over with Mine, de Pompadour the court of France, in addition to the alliance of Russia and the house of Saxonv, Frederick sought and obtained the alliance of England, and the seven years' war began (1756), of which the Prussian monarch became the hero, Laudon and Daun being his most effective Austrian antagonists. The war extended to almost all parts of the world, from the coast of Coromandel to Canada, and nearly all powers partook in it. The double peace of Paris and Hubertsburg (1763) terminated it to tin-advantage of Prussia and England, Frederick remaining now undisputed master of Silesia. Two years later Francis I. died, and was succeeded in the empire by his son Joseph II., and in Tuscany by Leopold, their sister Marie Antoinette being afterward married to the future French king Louis XVI. Joseph, however, enjoyed in the hereditary states of his mother only the rights of a co-regent, though his influence generally prevailed in foreign affairs, as in the case of the annexation of Galicia at the first division of Poland (1772), and of Huko-wina from Turkey (1777). The peace of Te-schen (1779) terminated, according to the energetic decision of the old empress, the war of the Bavarian succession.
A monument 60 ft. high, representing Maria Theresa surrounded by the principal statesmen of her time, is to be completed at Vienna in 1875. Her correspondence, comprising several previously unknown letters, has been published in French by Alfred von Arneth (3 vols.. Paris, 1874).