François Sebastien Charles Joseph de Croix, Count of Clerfayt or Clairfayt, (14 October 1733 - 21 July 1798), Austrian field marshal, was born at the Castle of Bruille in Hainaut in the Austrian Netherlands. He entered the Austrian army in 1753. In the Seven Years' War (1756 - 1763) he distinguished himself, earning rapid promotion, and receiving the decoration of the order of Maria Theresa. At the conclusion of the peace (Treaty of Hubertusburg, 15 February 1763), though still under thirty, he had already become a colonel.

During the outbreak in the Netherlands in 1787, Clerfayt, as a Walloon by birth, came under great pressure to abandon Joseph II, but he resisted all overtures, and in the following year went to the Turkish war with the rank of lieutenant field marshal. In an independent command Clerfayt achieved great success, defeating the Turks at Mehadia and Calafat.

In 1792, as one of the most distinguished of the emperor's generals, he received the command of the Austrian contingent in army of the duke of Brunswick , and at Croix-sous-Bois his corps inflicted a reverse on the troops of the French Revolution. In the Netherlands, to which quarter he transferred after Jemappes, he opened the campaign of 1793 with the victory of Aldenhoven and the relief of Maastricht, and on 18 March 1793 proved instrumental in causing the complete defeat of Dumouriez at Neerwinden. Later in the year, however, his victorious career suffered a reverse at Wattignies, and in 1794 he failed in West Flanders against Pichegru. In the course of the campaign. Clerfayt succeeded the duke of Saxe-Coburg in the supreme command, but he failed to make headway against the French, and had to recross the Rhine.

In 1795, now field marshal, he commanded on the middle Rhine against Jourdan, and this time the fortune of war changed. Clerfayt beat Jourdan at Höchst and brilliantly relieved Mainz. But Thugut did not approve Clerfayt's action in concluding an armistice with the French, so the field marshal resigned his command and became a member of the Aulic Council in Vienna. He died in 1798.

A brave and skilful soldier, Clerfayt perhaps achieved more than any other Austrian commander (except the archduke Charles) in the hopeless struggle of small dynastic armies against a French "nation in arms".

See von Vivenot, Thugut, Clerfayt, und Würmser (Vienna, 1869).