On 17 September, Dunsterforce had been disbanded and North Persia Force (Major-General W. M. Thomson) took over the command of the troops in the area. The Dunsterforce officers were allowed to choose to return to their regiments, join Indian battalions or stay on in Norperforce. Marshall was told by the War Office on 2 October, that an Ottoman request for an armistice was anticipated and he was to take as much ground as possible up the Tigris, to assist the British in Syria to advance on Aleppo. Marshall planned a advance up the Tigris, despite most of the transport being in Iran, making an advance to Aleppo out of the question. The advance began after the Ottoman armistice request and the Ottoman troops began a withdrawal on 24 October, until the Tigris Group ("Dicle Grubu") of the 6th Army was surrounded and forced to surrender on 29 October, at the Battle of Sharqat (23–30 October).