Dublin Castle, with the Medieval tower circa 1228, courtesy http://www.cityscouter.com/travelguides/dublin/Dublin-Castle.html.
In February of 1534 Gerald Fitzgerald, the 9th Earl of Kildare, was summoned to London and appointed his son, Thomas Fitzgerald, later known as Silken Thomas, as deputy governor of Ireland. The following June, Thomas heard rumours that his father had been executed in the Tower of London on order of his cousin, King Henry VIII. Thomas summoned the council, along with 140 gallowglasses, with silk fringes on their helmets (hence the nickname), and headed to St. Mary's Abby in Dublin where he publicly renounced his allegiance to King Henry VIII. The Chancellor , Archbishop John Allen, tried to persuade Thomas to have a change of heart, but the deputy governor was undeterred. The council issued a warrant for Thomas' arrest.
Dublin Castle alone supported the King of England. In July of 1534, Silken Thomas attacked Dublin Castle, but his army was routed. He ordered the archbishop to be executed, a move that lost his favour with the church. In the meantime, Thomas' father, who turned out to still be alive, passed away from an illness and Thomas became the 10th Earl. He retreated to Maynooth Castle.
Sometime between 1535 and 1538, King Henry the VIII was excommunicated and no longer posed a threat to Thomas. Thomas, after seeing his army dissipate, and seeing his allies submit one by one, requested a pardon of the English government. He was sentenced to prison time in the Tower of London with the promise that his life would be spared. Later, however, the prison time was commuted to a death sentence and Fitzgerald was hanged, along with his five uncles, in February of 1537. While Thomas' uncles were hanged, beheaded and quartered, Thomas was hanged, beheaded and properly buried. Silken Thomas' revolt played a major role in the creation of the Kingdom of Ireland in 1542.
Silken Thomas attacks Dublin Castle circa 1534 courtesy https://en.wikipedia.org/wiki/Thomas_FitzGerald,_10th_Earl_of_Kildare.