While all danger of a Christian rising in Constantinople was thus prevented, Mahmûd was maturing the plans which in 1825 made him at last an absolute ruler, at least in his own city. For seventeen years Mahmûd prepared for this great stroke. First by gifts and offices he detached many of the supporters of the Janissaries and the Ulemas from the party which supported them. Some less important members of the body were arrested for infraction of the laws and were publicly executed. Others were secretly made away with. The Sultan was surrounding himself with an elaborate spy system and with agents who were capable of dealing in detail with those whom he wished to be put out of the way. Lord Stratford de Redcliffe, in his "Memoirs," says: "I remember that in crossing the Golden Horn from time to time I had observed loose mats floating here and there upon the water, and that in answer to my enquiries I had been told in a mysterious manner that they had served for covering the bodies thrown after private executions into the harbour." All this was done slowly; the power of the Janissaries was gradually undermined; "almost unparalleled craft and cruelty," some observers called the process, but to Mahmûd it seemed absolutely necessary. In 1826 the Sultan perceived that the time limit had come. A meeting of all the chief functionaries of the Empire and chief officers of the Janissaries was held. They agreed to submit to the new military discipline and organisation which the Sultan designed. All signed their names. On June 12 the first exercises of the new order were begun. On the 16th the inferior officers and the soldiers declared that they would not submit. The revolt was proclaimed in the ancient manner. The kettles were overturned, and the whole force was called to arms. Mahmûd crossed from Bekistasch to the Seraglio; the standard of the Prophet was displayed; the city was filled with the troops upon whom the Sultan could rely; the Moslem population rallied round the green flag. The people assembled in the Atmeidan (the Hippodrome); Mahmûd went to the mosque of Ahmed. The Janissaries were summoned to submit to the new order. They in return demanded the destruction of the "subverters of the ancient usages of the Empire." Then their fate was sealed. They had advanced to the mosque of Bayezid; they were rapidly driven back and hemmed in in their quarters in the Etmeidan. Then from every side artillery was directed upon them. From his house in Pera Stratford Canning, at dinner, saw "two slender columns of smoke rising above the opposite horizon." What did they mean? The Sultan, he was answered, had fired the barracks of the Janissaries. The rest of the tragedy may best be told in Canning's own words:[45]