Armies in Ireland trace their origins to the legendary Fianna and their leader Finn mac Cumaill. From at least the eleventh century, the Irish kings maintained small permanent fighting forces later known as their teaghlach or lucht tighe—meaning "troops of the household." These were well-equipped and were divided into footmen and marcshluag (cavalry). Highly skilled professional soldiers, they were often given houses and lands among the king’s mensal lands. It was clear that, from the reign of Brian Boru (d. 1014), Irish kings could take large forces of spearmen, swordsmen, archers, slingers, and horsemen on campaign, often combining them in operations with naval forces. To put such forces into the field, Irish kings must have developed an extensive support network to maintain, arm, and feed their troops on campaign. The size of these armies and the destructive scale of Irish warfare were aptly demonstrated in 1151 at the battle of Moin Mor, where seven thousand soldiers fell, if the annals are to be believed. What characterized Irish warfare during this period was the rapid mobility of armies. For example, Ruaidri Ua Conchobair (d. 1198) developed large forces of highly mobile and well-armed horsemen—mainly drawn from the upper classes of his vassals. In comparison, Irish infantry forces seem mostly to have been lightly armed footmen. However, it is likely that the Irish elite soldiery had adopted Ostman-style chain mail armor; finds of armor-piercing arrowheads at Waterford show that some of its defenders wore chain mail. Moreover, Ruaidn perhaps developed his permanent foot soldiers of his teaghlach or lucht tighe into a form of heavy infantry—similar to the household jarls of the Anglo-Saxon kings. Another major development in the composition of Irish armies was the growing dependence of Irish kings upon mercenaries later known as ceithirne congbala (retained bands). And from the early 1100s, Irish kings—such as Muirchertach Mac Lochlainn (d. 1166) were looking abroad—recruiting Hebridean-Norse forces and fleets from the Western Isles of Scotland to serve in Ireland. The military power of a great king such as Ruaidn was maintained by the levy of Gaelic military service— illustrating the extent of a king’s overlordship over his vassals. All the able-bodied population—apart from the learned and the clergy—were eligible for service. A king’s principal military commander was the maras-gal (marshal), an office whose origins lay probably in the earlier dux luchta tige (the head of the king’s household). The marshal’s principal duty was the organization of the king’s army, particularly the levying and billeting of troops along with the fining of those who failed to render military service.
However, warfare and armies changed forever after the return in 1167 of Diarmait Mac Murchada (d. 1171) from Britain with English and Welsh mercenaries. The devastation of East Leinster by these forces demonstrated that they were vastly superior to their Irish opponents. Yet it would be a mistake to view Irish and English armies as uniracial. Other Irish kings soon followed Mac Murchada’s example of building his forces around an English spine; Domnall Mac Gilla Patraic of Osraige (d. 1185) hired Maurice de Pren-dergast in 1169 to resist Mac Murchada, and exemplified the fluid nature of military service, rendering feudal service to Richard de Clare (Strongbow, d. 1176). Further, Cathal Crobderg Ua Conchobair of Connacht (d. 1224) strengthened his forces in 1195 by employing the services of Gilbert de Angulo (d. 1212), demonstrating the hybrid nature of the forces in his pay.
On the other hand, English armies in Ireland were dependent upon military feudalism, whereby all royal tenants, both English and Irish, were obliged to render military service in the feudal host. Essentially, the arms of the feudal host were made up of knights, men at arms, footmen, archers, and hobelars (forces of lightly armed and mobile horsemen adapted to the conditions of Irish warfare). Throughout much of the thirteenth century, English armies continually demonstrated their superiority in pitched battles with the Irish. The major difference between the Irish and English armies of this time was the quality of their cavalry. In contrast with the lightly armed Irish horseman, the heavily armored English knight was mounted on a large horse known as a charger. The defeat at Athenry in September 1249 of Tairrdel-bach Ua Conchobair (d. 1266), king of Connacht, showed that Irish forces could not resist the massed charge of English cavalry. This led to innovations to balance the military equilibrium. In 1259, Aed son of Feidlim Ua Conchobair (d. 1274), prince of Connacht, formed a marriage-alliance with the Hebridean-Norse king of the Western Isles. As part of his bride’s dowry, he gained 160 fighting men known as galloglass—heavy infantry which fought in formations designed to counter English cavalry-charges.
The weakness of the Dublin government for much of the middle ages—combined with absence of a royal standing army—meant that English forces were to become increasingly hybrid. As time progressed, gallo-glass became a feature of English armies in Ireland. But the development of large private armies by the English magnates of Ireland was crucial to the survival of their power on the frontiers. Clearly, they were adopting Gaelic elements. In Ulster, the de Burgh earls adopted the buannacht (bonaght; the wages and provisions of a galloglass), which involved quartering galloglass throughout the earldom, while the earls levied the tuarastal (wages) of these elite soldiers upon the people. During the parliament of 1297, it emerged that English magnates often hired Irish troops, billeting them upon their own English tenants—prompting the outlawry of this practice. Other English magnates in Ireland billeted troops upon their tenants; it was reputed that Fitzgerald (d. 1463), seventh earl of Desmond, first imposed coinnmhead (coyne; billeting) upon his earldom. During the early decades of the fifteenth century James Butler (d. 1452), fourth earl of Ormond, imposed forces of "kernety" and galloglass throughout his lands in Tipperary and Kilkenny—granting them the right to take a cuid oidche (cuddy; a night’s portion of food, drink, and entertainment) from every freeholder’s house. The change in the composition of private English armies was dramatically illustrated in the usage by Desmond and Ormond of kernety—a form of military police, traditionally only in the service of Irish lords, for arresting offenders and acting as guards of a lordship. That Ormond instituted this form was remarkable—but even more remarkable was the fact that his 120 kernety were drawn evenly from the Purcells and the Codys, families of English lineage. The rise of the Fitzgerald earls of Kildare from 1456 further displayed the hybrid nature of armies in Ireland. In 1474, Thomas Fitzgerald (d. 1478), seventh earl of Kildare, established a permanent fighting force, the "Fraternity of St. George," comprising 160 archers and 63 spearmen. However, the Kildares’ real military strength lay in their large forces of Mac Domnaill galloglass—forcing the Leinster Irish to recruit galloglass of their own. Such was the power of the Kildares that they were able to billet their gallo-glass upon the Pale, levying "coyne and livery" upon Englishmen for their maintenance.
From the late 1510s, the English government became convinced of the necessity of reform in Ireland and gradually royal armies returned. The collapse of the Kildare rebellion in 1535 created a countrywide political vacuum, so the Dublin government sought to extend royal jurisdiction throughout the country, demanding the dissolution of all private armies and the abolition of coyne and livery. There was vehement resistance—particularly from the Irish lords. Towards the end of the sixteenth century, Irish leaders such as Aed Ua Neill (d. 1616), second earl of Tyrone, and Fiach Ua Broin (d. 1597) emerged to revolutionize Irish armies and warfare by adopting foreign ideas, tactics, training, and formations. Tyrone trained a red-coated Ulster army to fight in the Spanish tercio formation, using both pike and musket. He won great victories at Clontribret in 1595 and at Yellow Ford three years later, but his defeat at Kinsale in 1601 effectively ended resistance from coordinated Irish forces. However, the allegiance owed to the great lords was still hard to destroy completely. Indeed, it took the armies of Oliver Cromwell (d. 1656), lord protector of England, during the late 1640s and 1650s to finally tear up the last roots of the private armies.
