Sybourg was born Charles de Sibourg, a gentleman of French extraction and a Protestant,[1] and was said to have been an illegitimate son of Meinhardt, Duke of Schomberg.
[1] On 1 May 1694 he was promoted to the rank of major in Schomberg's 8th Horse (later 7th Dragoon Guards),[2] and on 1 March 1703 was appointed to the lieutenant-colonelcy of the regiment,[3] from which time he discontinued the de in his name, which was afterwards spelt Sybourg.
[4] He commanded the 8th Horse at the battles of Schellenberg, Blenheim and Ramillies,[1][2] and was promoted to the rank of brigader-general on 1 January 1707.
[6] On 1 January 1710 he was promoted to the rank of major-general,[7] and he succeeded the Earl of Orrery in the colonelcy of a newly raised regiment of foot on 8 December.
[1] In April 1725 he was made governor of Fort William in Scotland,[10][11] and it was reported that he amassed a fortune of £80,000.