Despite ending in an O'Rourke victory, they had lost complete control over the eastern half of their kingdom and the immediate chaos that ensued within West Breifne following the war left them without the power to retake it.

[3] This sparked a series of conflicts that lasted from 1257 to 1266 whereby Aedh O’Conor attempted to control the politics of West Breifne by instating and supporting his favoured candidates as kings, driving a wedge between the O’Rourkes, with devastating consequences for the unity and stability of the kingdom.

In 1258, with the war against Connacht still ongoing, Conchobar was betrayed and murdered by his own men with the assistance of Matha O'Reilly, king of East Breifne, who had also risen up in rebellion against Aedh O'Conor.

Domnall Carrach, Conchobar buide's brother, was inaugurated in 1307 and although he only ruled for four years until his death in 1311, his reign, but particularly that of his son Ualgarg Mór, marked the beginning of dynasty that would last for the rest of the kingdom's history.

Ualgarg Mór reigned for thirty years from 1316 to 1346 and restored power and prestige to West Breifne and the Ó Ruairc dynasty, which had been in decline for over a century and was under attack from almost all sides.

The kingship of West Breifne during this volatile period largely depended upon the often capricious support of the other clans within the kingdom and the surrounding area, notably the MacSamhradhain, Mac Raghnaill and Tellach-Dunchada.

These regional conflicts over succession never re-emerged following this due to the changing political landscape in Ireland, as English influence grew in the latter half of the 16th century and the clans united to fight against their encroachments.

The murder of Aodh Buidhe was carried out by the vassals of Tyrconnell in present-day County Sligo, as Lord Manus O'Donnell's daughter was Brian na Murtha's mother.

Gradually, many of the Irish kings began to tentatively work with the English (often through coercion), including Brian na Múrtha, who agreed to submit to the first composition of Connacht in 1576.

Under the 1576 agreement, the king of West Breifne was to answer to the Presidency-appointed High Sheriff of Leitrim, was denied the authority to rule over the other clans and, most crucially, was not allowed to maintain gallowglass.

This was the first time Tudor soldiers attacked West Breifne and was more about sending a message to Ó Ruairc that his kingdom was not impervious to English power than about tackling coyners.

Following the attack, Ó Ruairc sent his son Brian Óg na Samhtach to Dublin to complain on his behalf to Lord Deputy Henry Sidney of harassment by Malby and the Presidency.

[20] During the Anglo-Spanish War (1585–1604), Brian na Múrtha assisted at least eighty survivors of the Spanish Armada shipwreck off the County Sligo coast to depart the country in the winter of 1588.

[24] He travelled to Scotland in February 1591 bearing gifts (including four Irish Wolfhounds), in anticipation of a meeting with King James VI, seeking to raise an army of mercenaries and retake his kingdom.

[25] In consultation with the English ambassador, King James VI denied him an audience and was pressured by Queen Elizabeth I to arrest him and deliver him to England, citing the agreements made in the Treaty of Berwick.

[33] Sir George Bingham, brother of Richard and High Sheriff of Sligo based in Ballymote, and Brian Óg O’Rourke carried out the first acts of what was to become the Nine Years' War.

O’Rourke responded by hiring an army of mercenaries from Tyrconnell, Tyrone and Fermanagh, and set out with 1,100 men to Sligo in May 1593 and "there was little of that country which he did not plunder" – razing 13 villages and ransacking Ballymote itself.

His acceptance of this became the first of a number of ceasefires that characterized the Nine Years' War, where both England and the Irish lords had no intention of making peace but rather used the time to recover and regroup forces.

In February 1598, O’Rourke, accompanied by thirty West Breifne nobles, travelled to Boyle and submitted to Clifford, handing over the letters he had received from Philip II of Spain as a sign of his allegiance.

Brian Óg's fears proved correct as by early 1599, the rebel Irish lords were in complete control of Ulster and Connacht and raiding as far south as historic Thomond, before occupying Munster and most of Leinster the following year.

A substantial English force some 2,000-2,500 strong led by Sir Conyers Clifford was travelling north only to find that O’Rourke and 400 of his men had barricaded the pass and were guarding it on either side.

[45][46] Clifford was left mortally wounded and Brian Óg ordered his head to be cut off and sent to O'Donnell, who in turn sent it to the besieged O'Conors in Sligo as a message that no English help was coming.

The new commander of the English forces in Ireland Charles Blount, 8th Baron Mountjoy, employed a scorched earth policy which hit the Irish civilian and military population hard.

After ousting Tadhg, Brian Óg was called upon by Rory O'Donnell to assist him and provide him with soldiers in early 1602 but O'Rourke refused and remained in West Breifne to "protect his people".

[56] In late 1605 Sir Tadhg O’Rourke suddenly fell terminally ill and died aged 28, rumours of his poisoning abound – especially given the extraordinary circumstances that would lead to the dispossession of his sons and the subsequent Plantations of Leitrim.

Brian and his brother Aedh were to fall victim to the plotting of Attorney-General for Ireland John Davies, who set about undoing the "distasteful settlements" reached with the native Irish lords in the Treaty of Mellifont through legal means.

[59] Predictably, later that year a jury found that Mary O’Donnell's divorce of her first husband Donal O’Cahan was void, therefore her marriage to Tadhg was not recognised and their two sons Brian and Aedh were declared illegitimate.

[60] Lord Justice William Parsons travelled to London in February 1621 to convince George Villiers, 1st Duke of Buckingham, the king's favourite, to support the foundation of a new agency, the Irish Court of Wards, which would pave the way for new plantations in Ireland.

At Hampton Court, Aedh refused to give up his claim to his father's lands in the barony of Dromahair, County Leitrim, which had already been settled by British plantation owners and was jailed.

[64] Brian meanwhile continued to languish in prison, writing to Charles I and other English officials, petitioning them for a speedy trial so he could face his accusers, secure his freedom and recover his land.