FREDERICK WILLIAM (1620-1688), elector of Brandenburg, was born in Berlin in 1620. He is usually called " The Great Elector," and next to Frederick the Great he was the chief founder of the power of Prussia. A man of immense energy and determination, he devoted himself to his country, missing no opportunity, whether by intrigue or by force of arms, of adding to its extent and its influence. When at the age of twenty (1640) he succeeded to the electorate, lie found it almost ruined. His father, George William, being of feeble and vacillating character, had been unable to prevent the inroads of the contending armies during the Thirty" Years' War; and they had laid waste nearly the whole land, and treated the inhabitants with horrible cruelty. Frederick William, by skilful manage-ment, succeeded in getting rid of these barbarous hordes, and by slow degrees collected an army of about 30,000 men, which very effectually secured for him the respect of his neighbours. It was universally admitted that he was the true heir of the dukes of Pomerania, whose line died out in 1637; but at the Peace of Westphalia the lion's share of their territory was ceded to Sweden, Frederick William receiving only the eastern half of the country, shorn of Stettin. But he also obtained the bishoprics of Halberstadt, Minden, and Camin, with a promise of the archbishopric of Magdeburg. In 1655 war broke out between Sweden and Poland. Charles Gustavus, king of Sweden, compelled Frederick William to join him, and to do homage for Prussia, which had formerly been held in fief of Poland. After a battle of three days at Warsaw, the Poles were defeated (1656). In the following year the elector turned round and concluded an alliance with the Poles, receiving, by the treaty of Wehlau, in return for the promise of his aid an acknowledgment of Ohe complete independence of Prussia. Charles Gustavus uttered fierce threats of vengeance, but was prevented by sudden death from attempting to execute them. Frederick William had much trouble in inducing the states of Prussia to do homage to him as their sole lawful sovereign; but by a happy mingling of severity and kindness, he overcame in the end all opposition. As duke of Prussia he was now an absolutely independent sovereign, although still owing allegiance to the emperor for his other dominions. In 1666 he received, by the settlement of the Jülich-Cleve dispute, the duchy of Cleve proper, and the counties of Mark and Bavenstein; while Jülich and Berg were to fall to Brandenburg in the event of the Pfalz-Neuburg line dying out. When Louis XIV. invaded the Netherlands in 1674, Frederick William saw the danger which threatened Ger-many, and his own territories in particular; he therefore persuaded the emperor, various German princes, and the king of Denmark to form an alliance against the French. He soon withdrew from this contest, but in the war which began with the second French invasion of the Netherlands in 1674 he took a leading part. The Swedes sided with France, and were persuaded by Louis XIV. to invade Brandenburg, which they easily overran and devastated. The elector was unable to leave the seat of war for some time, but at last, in the summer of 1675, set out from Franconia, hastening forward with his cavalry, directing the infantry to follow as speedily as possible. Halting at Magdeburg, he heard that the Swedes were divided into three parties, and that the middle party was not more than forty miles off. Although overtaken only by a small body of his infantry, he rapidly advanced on this middle party, and on June 18, at Fehrbellin, after a severe struggle, de-cisively defeated it. The rest of the Swedes were then easily disposed of. He drove them not only from Brandenburg but from Pomerania, of which he became complete master. Between three and four years afterwards (about Christmas, 1678) they invaded Prussia, threatening Königsberg. In the dead of winter Frederick started from Berlin with a powerful force, and in the middle of January 1679 finally beat them, crossing the Frische Haff with 4000 men on sledges. After all, however, he did not obtain Pomerania, for when the peace of St Germain-en-Laye was concluded in 1679,Louis XIV. insisted on its being restored to his ally,the king of Sweden. Frederick William, indignant at Austria for allowing this, maintained for a time an alliance with France; but he had ultimately to cultivate the friendship of the emperor, from whom he hoped to obtain the Silesian principalities of Liegnitz, Brieg, and Wohlau, which, after 1675, he claimed as his by inheritance. He received the circle of Schwiebus, in Silesia (1686), on condition that he should withdraw his claim and send 8000 men to the help of the emperor in his war with the Turks. Two years afterwards he died. Although famous as a soldier, he was even greater as an administrator. He was the most econ-omical ruler of his age, yet did no injustice to any branch of the state service. Among the most important of his public works may be named the canal between the Oder and the Spree, which still bears his name. After the revocation of the edict of Nantes, he welcomed large numbers of French refugees to his dominions; and long before that time he had offered every encouragement to Flemish settlers, thus giving a powerful impulse to industry and commerce. He was twice married,—his first wife, Louise Henrietta, being a pious and energetic lady, endowed with so clear and pene-trating an understanding that her husband took no import-ant step without consulting her.

See Puffendorf, De rebus gestis Friderici Wilhelmi Magni (Berlin, 1695); Förster, Geschichte Friedrich Wilhelms (4th ed., Berlin 1855); W. Pierson, Der Grosse Kurfürst (Berlin, 1873); Carlyle, History of Friedrich II. of Prussia.