When the Confederates fused into the Royalist Alliance, he fought under James Butler, 1st Duke of Ormond in the Battle of Rathmines where he was wounded and taken prisoner.
in January 1636 Killeen married[14] Mabel, daughter of Nicholas Barnewall, 1st viscount Kingsland and Lady Bridget FitzGerald.
Christopher and Mabel had five sons (of which the younger three are poorly known): —and a daughter: In 1637 Killeen succeeded his father as the 2nd Earl of Fingall.
When the Rebellion broke out on 23 October 1641,[19] Fingall tried to stay neutral between the government and the rebel as most of the nobility and gentry of the Pale did.
On 16 November he was appointed a commissioner to negotiate with the rebels, "with a view to suspend for some time the sad effects of licentiousness and rapine, until the kingdom was put in a better posture of defence".
On 2 August 1649 Lord Fingall fought under James Butler, 1st Duke of Ormond at the battle of Rathmines where he was wounded and taken prisoner by the Parliamentarians.
[23] The Parliamentarians accused him of high treason, and his estates were confiscated by the English Commonwealth's Act for the Settlement of Ireland on 12 August 1652[24] and Beaulieu was given to Sir Henry Tichborne as tenant to the state by Cromwell.