in may 1586, bagenal was sent by his father to the court to report. he sought measures to weaken hugh o'neill, 2nd earl of tyrone, an enhancement of the role of the marshal, and a presidency in ulster with a shire hall and jail to dispense royal justice. whilst on his visit, he wrote to edward manners, 3rd earl of rutland (a relative of his wife) on 16 september 1586 to ask whether he had a parliamentary borough to spare; he was elected mp for both grantham and anglesey and chose the latter. he returned to ireland in september 1587 to deputize for his father. he succeeded his father as marshal of the army in ireland and chief commissioner for ulster in october 1590, and was sworn of the privy council. his proposals for action were not accepted, as a decision had been taken to adopt a conciliatory attempt to o'neill. to bagenal's contempt, o'neill asked for the hand of bagenal's sister mabel in marriage; he refused, but they eloped anyway.