In September 1879 he was despatched, along with Maurice Abraham Cohen an expert in the Urdu language, to Kabul to seek retribution for the death of Sir Louis Cavagnari, the British envoy there. He was also given the local rank of lieutenant-general on 11 November 1879. He was commander of the Kabul Field Force and brought at least 20 field guns (usually horse-drawn mobile cannons) with his army during the conquest and occupation of Kabul during the second phase of the war. His move against Kabul was sparked by the assassination of Cavagnari, the British envoy in Kabul and the official who had signed the Treaty of Gandamak with Amir Mohammad Yaqub Khan in May of that year.