Dermot was the King of Leinster in eastern Ireland and in 1166 had been defeated in battle by Tighernan O Ruairc another ruler in the region. Dermot was exiled and went to Normandy to the court of Henry II of England. Dermot asked for assistance in retaking his lands. Henry gave Dermot permission to find a willing army from either England or Wales and so Dermot approached Richard de Clare, the Earl of Pembroke and known as 'Strongbow', who agreed to help in return for several demands. These demands included Dermot's daughter's hand in marriage and to rule Leinster after Dermot's death. Dermot agreed to the conditions.
Dermot also recruited a number of knights from south Wales included the sons and grandsons of Nesta, the daughter of Rhys ap Tewdwr one of the kings of Wales. These heavily armoured knights arrived in Ireland in May of 1169 and were far superior to the poorly protected Irish warriors. Dermot was reinstated as King of Leinster.
Dermot was not happy to be just King of Leinster, he wanted to be High King of Ireland but he had to wait for the manpower that Stongbow had promised him. In 1170 a small force led by Raymond de Gros landed at Waterford on the East coast of Ireland. They constructed a base and waited for the Earl of Pembroke to arrive.
Richard de Clare, the Earl of Pembroke, landed in Ireland in the summer of 1170. His army captured Waterford and Dublin, and the Earl made Dublin his base for the winter months.
Dermot died in the spring of 1171 and Strongbow took control of Leinster. Henry II was concerned that the Earl could build himself a base in Ireland strong enough to create an independent state outside the control of the English King. Preparations were made and an army assembled to invade Ireland to deal with the Earl. But the invasion was not necessary as Strongbow left Ireland and travelled to England to meet the King. Strongbow agreed to that Henry controlled Dublin in return for his continued control of Leinster.
Henry II landed in Ireland in October or 1171 and received the homage of the Irish leaders. Traders were invited to Dublin where a colony of English was set up. Henry stayed in Ireland over the winter months returning to England in the spring of 1172.
|1166||Dermot exiled from Ireland|
|Dermot, the King of Leinster in eastern Ireland, was defeated in battle by Tighernan O Ruairc, another ruler in the region. Dermot was exiled and went to Normandy and the court of Henry II of England to ask for assistance in retaking his lands. Henry gave Dermot permission to find a willing army from either England or Wales and so Dermot approached Richard de Clare, the Earl of Pembroke who agreed to help in return for several demands. These demands were Dermot's daughter's hand in marriage and to rule Leinster after Dermot died.|
|1167||Aug||Dermot returns to Ireland|
|Dermot returned to Ireland but without an army. He was unable to retake Leinster and had to wait until the forces he had been promised arrived from Wales.|
|1169||May||Dermot retakes Leinster|
|Some the men promised to assist Dermot in Ireland landed at Bannow with the sons of Nesta. The poorly protected Irish warriors were no match for the armoured knights and archers that arrived from Wales. By the end of the year Leinster fell and Dermot once again became the King. After his victory Dermot was not satisfied with just ruling Leinster but wanted to become High King of Ireland. To fulfil his ambitions he had to wait for the arrival of Strongbow, the Earl of Pembroke, for that to be a possibility.|
|1170||May||Raymond de Gros lands in Ireland|
|Raymond de Gros arrived in Ireland in support of Dermot a few months ahead of Strongbow. He landed at Waterford and constructed a fort in which he and his men prepared for the arrival of the Earl.|
|Aug||Ireland attacked by Earl of Pembroke|
|Richard de Clare, the Earl of Pembroke, invaded Ireland with 200 knights in armour and up to a 1,000 foot-soldiers capturing Waterford easily and then Dublin on behalf of Dermot, the King of Leinster.|
|Sep 21||Dublin Captured by the Normans|
|Dublin fell to the Norman army.|
|Winter||The Earl at Dublin|
|After letting the population of Dublin leave, the Earl of Pembroke and his men spent the Winter in the city.|
|1171||Spring||Death of Dermot, King of Leinster|
|The agreement between the Earl of Pembroke and Dermot, the King of Leinster, was that if the Earl helped the King retake Leinster the Earl would become the ruler of Leinster when Dermot died. When the king died in the spring of 1171 the agreement fell apart due to the lack of support from Dermot's tribesmen. The tribesmen elected a nephew of Dermot's as the new king instead.|
|Jul||Henry plans invasion of Ireland|
|King Henry II had become concerned that Strongbow was building a strong base in Ireland, strong enough to become an independent state separate from England. Henry planned to take an army to Ireland to deal with Strongbow but Strongbow travelled to England and in September met Henry and promised his loyalty to the King.|
|Oct 17||Henry lands at Waterford in Ireland|
|Henry II travelled to Ireland to receive the homage of the Irish leaders. Traders were invited to Dublin where a colony of English was set up. Henry stayed in Ireland over the winter months returning to England in the spring of 1172.|
|1175||Oct 6||Treaty of Windsor|
|A treaty signed by Henry II and Rory O'Connor allowing O'Connor control of the areas of Ireland other than Leinster, Meath, Waterford and Dublin which were controlled by the English King. O'Connor agreed to pay Henry an annual sum of money and to provide one hide from each ten animals slaughtered every year.|
|1177||Construction of Carrickfergus Castle|
|Carrickfergus Castle was built by John de Courcy, the Norman knight who invaded and conquered the Irish region of Ulidia (Ulster).|
|Feb||The conquest of Ulidia (Ulster)|
|John de Courcy was a Norman knight who, with an army of around 320 men from Dublin, attacked the area of Ulidia (now Ulster) and captured its capital town Downpatrick. The king of the area, MacDunlevy, attempted to retake the town but was beaten back by de Courcy.|
|Jun||Courcy becomes lord of Ulidia|
|MacDunlevy, the native king of Ulidia (Ulster), was joined by the king of a neighbouring district and raised a large army to retake Ulidia from John de Courcy. They were also joined by several Irish bishops and many clerics. But the army was not able to defeat Courcy who then became lord of Ulidia.|
|1204||Dublin Castle construction started|
|King John ordered the construction of a castle at Dublin.|