Wars of the Roses -Impact in Ireland
I think it is important to understand a little of what was happening in England at the time to place the Irish history aspect in the context of that.
The Wars of the Roses is central in understanding this. There was a series of battles fought between two rival branches of the Plantagenet dynasty to see who would get control of the English throne in the 15th Century.
It is known as the War of the Roses as each family had a rose as its emblem, white for the York family and red for the House of Lancaster. The War of the Roses in Ireland would begin to unfold after the war in England.
The Battle of Bosworth was where this war had its last major battle and the house of York fell along with Richard III. The affairs of Ireland and England did become inextricably linked at this time.
In 1449, Richard the Duke of York was appointed governor of Ireland and he did impress the Irish people. He also impressed the Anglo-Irish and that was an uneasy position for the English.
England clearly supported Henry VI, whereas Ireland clearly supported Richard of York. The war of the Roses, which had been an ongoing battle between the noble houses of Lancaster and York started in 1399 with the death of Richard II It was Richard's son, Edward IV who eventually triumphed over the House of Lancaster and ascended to the throne in 1461.
This actually brought Irish and English relationships closer together. You can see how the War of the Roses intermingled with the Irish history and in many ways linked the two countries together, even though in a form of opposition.
I would now recommend reading about the Earls of Kildare in Ireland.