The Nine Years War began with a conflict over English efforts to maintain a string of garrisons along the southern border of Tyrone's territory in Ulster. The Irish leader promptly besieged the English garrison at Monaghan Castle, and Sir Henry Bagenal, commander of the English forces, marched out to its relief on 25 May (4 June New Style) from Dundalk, via Newry. His army was made up of 1,750 troops, including some veterans and certain companies newly arrived from the Spanish campaign in Brittany, but there were many recruits in the ranks. Bagenal's men were predominantly infantry, armed with muskets and pikes; there was also a small number of horsemen raised in the Pale.