What is the foundation of thy insolence and folly? [wrote Timur to Bayezid]. Thou hast fought some battles in the woods of Anatolia; contemptible trophies! Thou hast obtained some victories over the Christians of Europe; thy sword was blessed by the Apostle of God; and thy obedience to the precepts of the Koran in waging war against the infidel is the sole consideration that prevents us from destroying thy country, the frontier and bulwark of the Moslem world. Be wise in time; reflect; repent; and avert the thunder of our vengeance which is yet suspended over thy head. Thou art no more than an ant; why wilt thou seek to provoke the elephants? Alas, they will trample thee under their feet. Bayezid replied in terms of the greatest indignation. He protested that Timur had never triumphed unless by his own perfidy and the vices of his foes. Thy armies are innumerable: be they so; but what are the arrows of the flying Tartars against the scimitars and battle-axes of my firm and invincible Janissaries? I will guard the princes who have implored my protection; seek them in my tents. The cities of Arzingan and Erzerum are mine; and unless the tribute be paid I will demand the arrears under the walls of Tauris and Sultania. And he added an insult of a yet grosser kind which, by its allusion to the harem, was the worst that could be devised by a Moslem:— If I fly from thy arms may my wives be thrice divorced from my bed; but if thou hast not courage to meet me in the field, mayest thou again receive thy wives after they have thrice endured the embrace of a stranger. After this interchange of abuse Timur determined, in 1400, to attack and invade Asia Minor from Armenia, at the head of a horde of armed men, estimated by historians at not less than eight hundred thousand. He laid siege to Sivas, in Cappadocia, on the Armenian frontier, which had only been captured by Bayezid about three years previously. It was now defended by a garrison of Turks, under command of Ertoghrul, the eldest son of Bayezid. The fortifications were immensely strong, but Timur was ready to sacrifice any number of men in assaulting and capturing the city. He employed six thousand miners in undermining its defences with galleries and propping up the walls temporarily with timber smeared with pitch. When the mines were completed, fire was applied to the timber, and the walls gradually sank into the cavities laid open to them, and afforded entrance to the assaulting columns. The city was captured. Four thousand of its defenders were buried alive by order of Timur, and Ertoghrul was executed.