Maria Theresa, empress of Austria, daughter of the Emperor Charles VI., a queenly woman; was in 1736 married to Francis of Lorraine; ascended the throne in 1740 on the death of her father, associating her husband with her in the government under the title of Francis I.; no sooner had she done so than, despite the Pragmatic Sanction (q.v.), which assured her of her dominions in their integrity, she was assailed by claimants one for this and one for another portion of them, in particular by Frederick the Great, who by force of arms wrenched Silesia from her and kept it fast; the war thus occasioned is known as the war of the Austrian Succession, which lasted seven years, and was concluded by the Peace of Aix-la-Chapelle in 1748; this peace, however, was soon broken, and Maria, backed by France and counselled by Kaunitz, renewed hostilities in the hope of compelling Frederick to restore what he had taken; all in vain, for the end of this war, known as the Seven Years' War, was to leave Frederick still in possession of the territory which he had sliced from her empire as in the former; in the interim of these wars Maria devoted her attention to the welfare of her subjects, who were conspicuously loyal to her, and before the end of her reign she saw what she had lost made up to her in a measure by the partition of Poland, in which she took part (1717‒1780).
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Maria Louisa * Mariamne