He returned with Gordon as second-in-command on his journey to Khartoum commencing with departure from Victoria station in February 1884. Wounded during the siege, Stewart led an attempt to break the blockade aboard the Steamer "Abbas" in September 1884, along with the British consul Frank Power (who was also the correspondent from "The Times"), the French consul Léon Herbin, and other residents of Khartoum. The attempt failed when the "Abbas" ran aground on a rock near Abu Hamad. All passengers and crew were killed by Arab tribes ashore. Gordon learned of this a few weeks later when he received a letter from the Mahdi that quoted from letters that Stewart had been carrying with him on the "Abbas".