In 1610 he served at the siege of Juliers under Sir Edward Cecil. In 1616 he yielded up the cautionary town of Brielle to the Dutch on the repayment by them of the loans received from England, receiving a life pension of £800 in compensation for his loss of the governorship. Two years later Sir Horace received from Maurice the governorship of Utrecht. He had previously aided the prince in disarming and suppressing the provincial levies, raised on behalf of Johan van Oldenbarnevelt.