The son of a lawyer from Pau, Bernadotte was an NCO in the pre-revolutionary French Army and commissioned in late 1791. He fought the First Coalition on the Rhine and in the Flanders, leading a brigade at Fleurus and becoming a divisonal general in October 1794, before taking part in the Italian campaigns of 1796-97. He remained in Italy until 1798, when he was ambassador to Vienna for a few days before the breakdown of diplomatic relations with Austria.
An ostentatiously passionate republican, and trusted by the Directory government, he began the War of the Second Coalition commanding 48,000 troops on the northern sector of the Rhine around Mannheim, but was forced to retreat after Jourdan's failure at Stockach and quit his command for Paris shortly afterwards. Given the job of war minister from July 1799, he was dismissed in September but remained an influential political figure in Paris when the November Brumaire coup brought Napoleon to power.
Bernadotte became a state councillor and received an army command in 1800, rewards for not actually opposing the coup, and was appointed governor of Hanover in 1804. In May that year he was one of the original Marshalate, and commanded I Corps on the northern wing of the Grande Armée's adavance into Bavaria against the Third Coalition in 1805.
An impressively tall and handsome figure, apparently much given to boasting, Bernadotte was one of Napoleon's least aggressive commanders. His corps was at Ulm and Austerlitz in 1805, but he was threatened with court martial the next year when it failed to join the Battle of Auerstedt. He survived Napoleon's anger, perhaps because he was married to the emperor's former lover Désirée Clary, and led the subsequent French pursuit operation, making important new friends by his lenient treatment of Swedish prisoners of war at Lübeck.
After commanding occupying forces in northern Germany, Bernadotte was returned to frontline command in 1809, leading Saxon forces (as IX Corps) against the Fifth Coalition, but he was dismissed on the spot during an inept performance at Wagram and again relegated to secondary duties. Sent to command forces facing the British Walcheren expedition, he was sacked for the last time in September after an illjudged outburst of boasting was reported to Napoleon.
Anxious to cultivate French friendship, and misreading his current status, the Swedish States- General elected Bernadotte as heir to the childless King Charles XIII in August 1810. The new Crown Prince of Sweden abandoned France for his adopted country, taking effective control over affairs of state and initiating alliance with Russia by the St Petersburg treaty of 1812. The following year he committed Sweden to the Sixth Coalition and led his army in Germany, inflicting a major defeat on Ney's corps at Dennewitz in September 1813 but displaying his usual slow caution in arriving late at the crucial Battle of Leipzig in October. The campaign embraced tha almost incidental invasion of Danish Holstein, helping Sweden's acquisition of Norway from the Danes by the Treaty of Kiel in January 1814.
Bernadotte's Swedes played a relatively minor role in the 1814 campaign for France, concentrating on mopping-up operations in northern Germany and the Low countries. Satisfaction of Swedish territorial ambitions, along with his rather improbable belief that he might succeed Napoleon, influenced his reluctance to fight on French soil, and he kept Sweden out of the Seventh Coalition in 1815.
Though his military failings owed something to Napoleon's discouragement of tactical initiative, it is generally agreed that Bernadotte was a better monarch than soldier. His reign as king of Sweden (1818-1844) was characterized by liberal reform and harmonious relations with parliament, and his dynasty outlasted any of Napoleon's royal creations, remaining on the throne at the end of the Twentieth century.
Source: Dictionary of the Napoleonic Wars, ed. S. Pope, London: Collins, 1999