The cordon was initially under the command of Colonel J. M. Wilkeley before it was taken over by Reginald Dyer in February 1916. The cordon's task was to "intercept, capture or destroy any German parties attempting to enter Sistan or Afghanistan", to establish an intelligence system, and to watch the Birjand-Merked road. Persian subjects were not to be targeted as long as they were not accompanying Germans or acting as their couriers, and as long as Persia remained neutral. Following the Revolution in Russia, the Malleson Mission was sent to Trans-Caspia and the Seistan Force became the main line of communication for the mission. With the withdrawal of the force from Trans-Caspia, the troops in Persia were withdrawn; the last elements left in November 1920. British efforts against the conspiracy and the expedition began in Europe. Even before Mahendra Pratap met with the Kaiser, attempts were made by British intelligence to assassinate V.N. Chatterjee while he was on his way to Geneva to invite Pratap to Berlin. British agents were present in Constantinople, Cairo, and Persia. Their main efforts were directed at intercepting the expedition before it could reach Afghanistan, and thence to exert pressure to ensure that the Emir maintained his neutrality. Under the efforts of Sir Percy Sykes, British intelligence officers in Persia intercepted communications between the expedition and Prince Reuss in Tehran through various means. Among these were letters captured in November 1915 in which von Hentig gave details of the meetings with the Emir, and messages from Walter Röhr outlining the requirements for arms, ammunition, and men. The most dramatic intelligence coup was a message from von Hentig asking for a thousand Turkish troops and the necessity for "internal revulsions" in Afghanistan if need be. This message found its way to Russian intelligence and thence to the Viceroy, who passed on an exaggerated summary, warning the Emir of a possible coup funded by the Germans and a threat to his life. In mid-1916, intelligence officers in Punjab captured letters sent by the Indian provisional government's Ubaidullah Sindhi to Mahmud al-Hasan, which were addressed to the Turkish authority and the Sharif of Mecca. The letters, written in Persian on silk cloth, were sewn into a messenger's clothing when he was betrayed in Punjab. The event was named the Silk Letter Conspiracy. In August 1915, Mahendra Pratap's private secretary, Harish Chandra, had returned to Switzerland after a visit to India, at which time he had carried messages to various Indian princes.