On the news of the murder of Cavagnari at the Siege of the British Residency in Kabul, Warburton was nominated chief political officer with General Sir Robert Onesiphorus Bright, commanding the Jalalabad field force. He joined the force on 10 October, and proceeded to Jalalabad to ascertain the revenues of the district. In April 1880, he was invalided to England, and he did not return to the Khyber Pass until 16 February 1882. From that time he remained on the frontier almost continuously until his retirement.