In 1597, the English
Lord Deputy of Ireland, Thomas Burgh, built a new fort on the river
Blackwater five miles northwest of the English government's garrison town
Armagh. Soon after it was built,
Hugh O'Neill, Earl of Tyrone, laid
siege to it. In 1598, with the besieged garrison running low on supplies, the English government debated whether to abandon the fort, as it was too far into O'Neill's home territory to be sustainable. It was six and a half miles from the O'Neill stronghold of
Dungannon. Sir Henry Bagenal argued the fort should be re-supplied, and in early August 1598 was appointed to lead the expedition. According to the
Annals of the Four Masters: "When O'Neill had received intelligence that this great army was approaching him, he sent his messengers to
O'Donnell, requesting of him to come to his assistance against this overwhelming force of foreigners who were coming to his country. O'Donnell proceeded immediately, with all his warriors, both infantry and cavalry, and a strong body of forces from
Connacht, to assist his ally against those who were marching upon him. The Irish of all the province of Ulster also joined the same army, so that they were all prepared to meet the English before they arrived at Armagh". Bagenal's army marched from Dublin to Armagh. Meanwhile, O'Neill's troops had dug trenches in the countryside between Armagh and the Blackwater fort, blocked the roads with felled trees, and set up brushwood
breastworks. The countryside was hilly with
drumlins and was made up of woodland, bog and some fields. In Armagh, Bagenal was aware that the five miles to the besieged fort was laced with ambush positions, but believed his army could handle the hit-and-run tactics and that he would win any pitched battle. With the main road blocked, Bagenal chose to march along a series of low hills and cross the
River Callan.
Opposing forces Bagenal was the English army commander in chief (marshal) of
Ulster for a decade (beginning in 1587 as his father's deputy), gaining extensive experience fighting against the Maguires and other Irish lords. He had a bitter grudge against O'Neill, who some years earlier had eloped with his sister
Mabel. He was familiar with the territory. He commanded 3,500 footsoldiers. Bagenal's footsoldiers were armed with the standard weapons of the day:
pikes and
muskets. Standard formation when marching through hostile territory was musketeers in outside columns, able to fire out, and pikemen on the inside able to relieve the musketeers in the event of a sustained charge against the column. Bagenal also had 350
cavalry and several pieces of
artillery. The cavalry were commanded by Sir Calithenese Brooke. A troop of cavalry was commanded by Maelmora O'Reilly, who was deemed to be lord of
East Breifne by
Queen Elizabeth I. This was not recognised within the East Breifne and Maelmora had no authority there as it had risen up in rebellion. Maelmora was the eldest son of Sir John O'Reilly, Lord of East Breifne, who had died fighting against the English in 1596. Maelmora was slain in the battle of the Yellow Ford. The strength of O'Neill's army is estimated to have been 5,000. O'Neill's army was unlike earlier Irish armies, as possibly 80% of his men were armed with
calivers, which was a lighter and more portable version of the musket. These were supported by pikemen, and targeteers; Gaelic soldiers with sword and buckler who'd been trained by Spanish advisors, gave close protection to Tyrone's skirmishers. O'Neill had several English and Spanish military advisors in his pay, as well as many Irish officers with experience in mainland Europe, who trained his troops in the use of modern weaponry. However, his army was not the same as the
pike and shot deployed by the English. O'Neill developed a hybrid army which maximised his infantry's firepower while maintaining the key Irish advantage of mobility. The earl had less success modernising his cavalry, who carried their spears over-arm, either thrusting or throwing them at close quarters in the traditional way. ==The battle==