Frederick William II of Prussia (1744-1797, r.1786-1797) was the king of Prussia at the start of the French Revolutionary Wars, and led Prussia into the War of the First Coalition, before losing interest and taking his country out of the war early in 1795.
Frederick William was the son of Prince August Wilhelm (the second son of Frederick William I of Prussia) and a nephew of Frederick the Great. He became heir to the throne after his father's death in 1758, and was thus heir for almost thirty years. He had some experience of military service, first during the Seven Years War, and later as a senior commander during the War of the Bavarian Succession.
Frederick William II came to the throne after the death of Frederick the Great in 1786. One of the few benefits of his accession was the return to service of a number of able officers who had fallen out with Frederick, amongst them the future Marshal Blücher and General Yorck.
Although Frederick William is usually dismissed as a poor monarch, he did begin some reforms, including introducing military pensions, somewhat improving the military administration and expanding the light infantry. These reforms were generally well received at the time, but much of Frederick William's reign was dominated by the French Revolution, which began within three years of his coming to the throne.
Frederick William had already intervened once to oppose a revolution, in this case in the Netherlands in 1787, when his troops helped prop up the House of Orange.
Frederick William was horrified by the French Revolution, but at first he was more interested in affairs in Poland, where the country was in the process of being pulled apart by her neighbours. The revolutionaries were thus left along for the first
After Leopold became Holy Roman Emperor in 1790 the relationship between Austria and Prussia greatly improved and unlike his uncle Frederick William tended to follow the Austrian lead in foreign affairs. In August 1791 Frederick William and Leopold issued the Declaration of Pillnitz, in which they declared their willingness to cooperate with other European powers to restore King Louis XVI to power in France.
Despite this bellicose declaration, Austria and Prussia didn't agree a formal alliance until 7 February 1792, and when war came it was the French who declared war on Austria (20 April 1792), at least in part because of internal revolutionary politics. This led to the formation of the First Coalition on 26 June, when the alliance came into force.
Frederick William believed that France would be weakened by the revolutionary chaos. The Prussian field marshal Karl Wilhelm Ferdinand, duke of Brunswick, became commander-in-chief of the Allied army, but the King accompanied the army and interfered in its operations. Brunswick wanted to conduct a typically slow eighteenth century campaign, establishing a strong base on the French frontier in 1792 before invading in 1793. Frederick William insisted on an immediate invasion, and reluctantly Brunswick cross the border. The French soon got behind the Allies, and Brunswick decided to attack their lines. The resulting battle of Valmy (20 September 1792) saw the French army stand up to an Allied artillery bombardment and two weak infantry advances. After a ten day long standoff, Brunswick decided to retreat back to the border. The Revolution had been saved.
After a series of Allied failures in the summer of 1793 Frederick William lost interest in the war, and returned to Prussia to concentrate his efforts against Poland. In 1794 the Duke of Brunswick resigned his command in protest against interference from the King. Frederick William agreed to take personal command of the Prussian army fighting the French, but at the last minute decided to go to Poland instead, to help put down Tadeusz Kosciuszko's revolt.
Towards the end of 1794 Frederick William realised that the French were not as weak as he had expected, and he entered into negotiations with the French. On 5 April 1795 the French and Prussians signed the Treaty of Basle, and Prussia withdrew from the First Coalition. Large parts of northern Germany thus became neutral, and the French withdrew from any Prussian territory east of the Rhine. This treaty was seen as an act of betrayal by the other members of the First Coalition, and damaged Prussia's reputation.
Frederick William was also motivated to make peace by his desire to concentrate on Poland. In 1793 Prussia gained territory in the Second Partition of Poland, and in 1795 that continued with the Third Partition. These territorial gains didn't provide any real benefits during Frederick William II's reign, as the area took more money to control than it generated. They would be lost for good under his son Frederick William III.
Frederick William was legally married twice, and his heir Frederick William III was the son of his second wife, Fredericka Louise of Hesse-Darmstadt. His first marriage, to Princess Elisabeth Christiane Ulrike of Brunswick, ended in divorce in 1769. He also carried out two polygamous marriages (to Elisabeth Amalie and Sophie Juliane) and had one acknowledged mistress (Wilhelmine Enke). At the end of his reign Prussia was almost bankrupt.
During his reign he was over-influenced by the mystics Johann Wöllner and Johann von Bischoffswerder, and the former became a virtual prime minister.