His next enterprise in the Netherlands was in connection with the siege of 's-Hertogenbosch, one of the chief military positions in Brabant, undertaken by Prince Frederic Henry in April 1629. Sir Edward Vere (born ca. 1580), the illegitimate son of Horatio's first cousin Edward, Earl of Oxford, was mortally wounded in the lines on 18 August a few weeks before the place was finally surrendered. A large number of Englishmen who were afterwards distinguished soldiers served under Vere in the trenches at Den Bosch. Among them were: Thomas Fairfax and Philip Skippon, the future organisers of the New Model Army; Jacob Astley, Thomas Glemham, the future royalist generals; Sir John Borlase, and Henry Hexham, the historian of the Dutch wars. Fairfax, Skippon, and George Monck, particularly, were his pupils in the art of war.