Horn, Or Hoorne Philip II. de Montmorency-Nivelle,. count of, a Flemish statesman, born in 1522, executed at Brussels, June 5, 1568. His father was descended from the noble French family of Montmorency, and on his mother's side he was related to Lamoral Egmont, with whose fate his own was destined to be unhappily linked. His mother, becoming a widow when he was about eight years of age, was married again to John, count of Horn, one of the wealthiest nobles of the Netherlands, who, having no children of his own, left his estates to his wife's children, on the condition that they should assume his name. Philip count of Horn thus at the outset of his career became one of the most powerful of his order, and subsequently received from the emperor Charles V. and from Philip II. the appointments of governor of Geldern and Zutphen, admiral of the Flemish fleet, and councillor of state. He fought with reputation in the battles of St. Quentin and Gravelines, and in 1559 accompanied Philip II. to Spain, where during a residence of two years he is supposed to have received information of the designs of the Spanish court against the Netherlands, and to have communicated them to the prince of Orange. Returning to the Netherlands, he joined Orange and Egmont in resisting the aggressive policy of Philip, and in urging him to recall Cardinal Granvelle; and with them he retired from the state councils until the departure of the obnoxious minister.

Like Egmont and William of Orange, he also declined to sign the compromise of Breda against the introduction of the Spanish inquisition into the Netherlands, in which the greater part of the lesser Flemish nobility were interested; but his accidental presence with his friends at a banquet at which the signers of the compromise first took the name of gueux or "beggars" (April, 1566), proved afterward a serious charge against him. After the excesses committed by the iconoclasts in the same year, he "was instrumental in preventing a general massacre of Catholics at Tour-nay; but his permission to Protestants to worship in the clothiers' hall, within the city, subjected him to a severe reprimand from the regent Margaret, in consequence of which he offered to resign all his offices, and wrote a letter to the king complaining of the policy pursued by the regent, and protesting that he would no longer treat of affairs of business with women. His possessions had meanwhile been very considerably reduced by disbursements made in the king's service, for which he had received no recompense; and he retired to his estates, discontented and smarting under many injuries real or fancied, but still loyal to the crown and indisposed to accept the doctrine of resistance already broached by the prince of Orange. He refused at first to take the new test oath exacted by Margaret; but after the retirement of the prince to Germany he made her an offer of his services, and agreed to take the oath.

This new proof of loyalty was of no avail with Philip, who had long decided upon the death of Horn; and upon the arrival of Alva in Brussels, both Egmont and Horn were enticed to that city and there arrested, Sept. 9, 1507, on a charge of treason and other high offences. (See Egmont.) His wife and mother made ceaseless efforts to obtain for him a fair trial, and, as in Egmont's case, appeals for royal clemency in his behalf were made to Philip by potentates in all parts of Europe. He was executed after Egmont, and met his fate with composure, although, when his sentence was first made known to him, he protested against its injustice, exclaiming that it was a poor requital for 28 years of faithful services.