Frederick-Armand duke of, a distinguished officer, sprung from an illustrious family in Germany, and the son of Count Schomberg by an English lady, daughter of Lord Dudley, was born in 1608. He was initiated into the military life under Frederick-Henry prince of Orange, and afterwards served under his son William II. of Orange, who highly esteemed him. He then repaired to the court of France, where his reputation was so well known, that he obtained the government of Gravelines, of Fumes, and the surrounding countries. He was reckoned inferior to no general in that kingdom except Marechal Turenne and the Prince of Condé; men of such exalted eminence that it was no disgrace to acknowledge their superiority. The French court thinking it necessary to diminish the power of Spain, sent Schomberg to the affluence of the Portuguese, who were engaged in a war with that country reflecting the succession to their throne.—Schomberg's military talents gave a turn to the war in favour of his allies. The court of Spain was obliged to solicit peace in 1668, and to acknowledge the house of Braganza as the just heirs to the throne of Portugal. For his great services he was created Count Mentola in Portugal; and a pension of 5000l. was bestowed upon him, with the reverence to his heirs.

In 1673 he came over to England to command the army; but the English at that time being disgusted with the French nation, Schomberg was suspected of coming over with a design to corrupt the army, and bring it under French discipline. He therefore found it necessary to return to France, which he soon left, and went to the Netherlands. In the month of June 1676, he forced the prince of Orange to raise the siege of Maastricht; and it is said he was then raised to the rank of Marechal of France. But the French Dictionnaire Historique, whose information on a point of this nature ought to be authentic, says, that he was invested with this honour the same year in which he took the fortres of Bellegarde from the Spaniards while serving in Portugal.

Upon the revocation of the edict of Nantes, when the persecution commenced against the Protestants, Schomberg, who was of that persuasion, requested leave to retire into his own country. This request was refused; but he was permitted to take refuge in Portugal, where he had reason to expect he would be kindly received on account of past services. But the religious zeal of the Portuguese, though it did not prevent them from accepting affluence from a heretic when their kingdom Schomberg's kingdom was threatened with subversion, could not permit them to give him shelter when he came for protection. The inquisition interfered, and obliged the king to send him away. He then went to Holland by the way of England. Having accepted an invitation from the elector of Brandenburg, he was invested with the government of Ducal Prussia, and appointed commander-in-chief of the elector's forces. When the prince of Orange failed to England to take possession of the crown which his father-in-law James II. had abdicated, Schomberg obtained permission from the elector of Brandenburg to accompany him. He is supposed to have been the author of an ingenious stratagem which the prince employed after his arrival in London to discover the sentiments of the people respecting the revolution. The stratagem was, to spread an alarm over the country that the Irish were approaching with fire and sword. When the prince was established on the throne of England, Schomberg was appointed commander in chief of the forces and master of the ordnance. In April 1689 he was made knight of the garter, and naturalized by act of Parliament; and in May following was created a baron, earl, marquis, and duke of the kingdom of England, by the name and title of baron Teys, earl of Brentford, marquis of Harwich, and duke of Schomberg. The House of Commons voted to him £100,000, as a reward for his services. Of this he only received a small part; but after his death a pension of £5000 a-year was bestowed upon his son.

In August 1689 he was sent to Ireland to reduce that kingdom to obedience. When he arrived, he found himself at the head of an army consisting only of 12,000 foot and 2000 horse, while King James commanded an army three times more numerous. Schomberg thought it dangerous to engage with so superior a force, and being disappointed in his promised supplies from England, judged it prudent to remain on the defensive. He therefore posted himself at Dundalk, about five or six miles distance from James, who was encamped at Ardee. For six weeks he remained in this position, without attempting to give battle, while from the wetness of the season he lost nearly the half of his army. Schomberg was much blamed for not coming to action; but some excellent judges admired his conduct as a display of great military talents. Had he risked an engagement, and been defeated, Ireland would have been lost. At the famous battle of the Boyne, fought on the 1st July 1690, which decided the fate of James, Schomberg passed the river at the head of his cavalry, defeated eight squadrons of the enemy, and broke the Irish infantry. When the French Protestants lost their commander, Schomberg went to rally and lead them on to charge. While thus engaged, a party of King James's guards, which had been separated from the rest, passed Schomberg, in attempting to rejoin their own army. They attacked him with great fury, and gave him two wounds in the head. As the wounds were not dangerous, he might soon have recovered from them; but the French Protestants, perhaps thinking their general was killed, immediately fired upon the guards, and shot him dead on the spot. He was buried in St Patrick's cathedral.

Bishop Burnet says, Schomberg was "a calm man, Schomberg, of great application and conduct, and thought much better than he spoke; of true judgement, of exact propriety, and of a humble and obliging temper."