Maximilian I Joseph (27 May 1756 – 13 October 1825) was Duke of Zweibrücken from 1795 to 1799, Prince-Elector of Bavaria (as Maximilian IV Joseph) from 1799 to 1806, then King of Bavaria (as Maximilian I Joseph) from 1806 to 1825. He was a member of the House of Palatinate-Birkenfeld-Zweibrücken, a branch of the House of Wittelsbach. Maximilian, the son of the Count Palatine Frederick Michael of Zweibrücken-Birkenfeld and Maria Francisca of Sulzbach, was born on 27 May 1756 at Schwetzingen, between Heidelberg and Mannheim. After the death of his father in 1767, he was left at first without parental supervision, since his mother had been banished from her husband's court after giving birth to a son fathered by an actor. Maximilian was carefully educated under the supervision of his uncle, Duke Christian IV of Zweibrücken. He became Count of Rappoltstein in 1776 and took service in 1777 as a colonel in the French army. He rose rapidly to the rank of major-general. From 1782 to 1789, he was stationed at Strasbourg. By the outbreak of the French Revolution, Maximilian exchanged the French for the Austrian service and took part in the opening campaigns of the French Revolutionary Wars. On 1 April 1795, Maximilian succeeded his brother Charles II as Duke of Zweibrücken, however his duchy was entirely occupied by revolutionary France at the time. On 16 February 1799, he became Elector of Bavaria and Count Palatine of the Rhine and Duke of Berg upon the extinction of the Palatinate-Sulzbach line at the death of Elector Charles Theodore of Bavaria. In foreign affairs, Maximilian Joseph's attitude was, from the German point of view, less commendable. He never had any sympathy with the growing sentiment of German nationality, and his attitude was dictated by wholly dynastic, or at least Bavarian, considerations. Until 1813, he was the most faithful of Napoleon's German allies, the relationship cemented by the marriage of his eldest daughter to Eugène de Beauharnais. His reward came with the Treaty of Pressburg (26 December 1805), by the terms of which he was to receive the royal title and important territorial acquisitions in Swabia and Franconia to round off his kingdom. He assumed the title of king on 1 January 1806. On 15 March, he ceded the Duchy of Berg to Napoleon's brother-in-law Joachim Murat. The new King of Bavaria was the most important of the princes belonging to the Confederation of the Rhine, and remained Napoleon's ally until the eve of the Battle of Leipzig, when by the Treaty of Ried (8 October 1813) he made the guarantee of the integrity of his kingdom the price of his joining the Allies. On 14 October, Bavaria made a formal declaration of war against Napoleonic France. The treaty was passionately backed by Crown Prince Ludwig and by Marshal von Wrede.

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