OF THE EOMAN EMPIRE 9 retaliation of the Thracian peasants. An army of Bulgai-ians was attracted from the Danube by the gifts and promises of Leo ; and these savage auxiharies made some atonement for the evils which they had inflicted on the empire, by the defeat and slaughter of twenty-two thousand Asiatics. A report was dexterously scattered that the Franks, the unknown nations of the Latin world, Avere arming by sea and land in the defence of the Christian cause, and their formidable aid was expected with far different sensations in the camp and city. At length, after a siege of thirteen months,^ the hopeless Moslemah received Pauure and from the caliph the welcome permission to retreat. The march slraTen^ of the Arabian cavalry over the Hellespont and through the provinces of Asia was executed without delay or molestation ; but an army of their brethren had been cut to pieces on the side of Bithynia, and the remains of the fleet was so repeatedly damaged by tempest and fire that only five galleys entered the port of Alexandria to relate the tale of their various and almost incredible disasters.^ In the two sieges, the deliverance of Constantinople may be invention chiefly ascribed to the novelty, the terrors, and the real efficacy the tocel of the Greek ^fire}'^ The important secret of compounding and directing this artificial flame was imparted by Callinicus, a native of Heliopolis in Syria, who deserted from the service of the caliph to that of the emperor.^^ The skill of a chymist and engineer was equivalent to the succour of fleets and armies ; and this discovery or improvement of the military art was fortunately 1^ Both Nicephorus and Theophanes agree that the siege of Constantinople was raised the isth of August (a.D. 718) ; but, as the former, our best witness, affirms that it continued thirteen months, the latter must be mistaken in supposing that it began on the same day of the preceding year. I do not find that Pagi has re- marked this inconsistency. [Tabari places the beginning of the siege in a.h. 98 = A.D. 716-17, but does not mention the month; and he makes Omar II. recall Maslama in A.H. 99 (Aug. 25, 717 — Aug. 2, 718). See Tabari, ed. de Goeje, ii. 1342.] iIn the second siege of Constantinople, I have followed Nicephorus (Brev. p. 33-36 [pp. 53-4, ed. de Boor]), Theophanes (Chronograph, p. 324-334 [..m. 6209, 6210]), Cedrenus (Compend. p. 449-452 [i. 787, ed. Bonn]), Zonaras (tom. ii. p. 98- 102 [xv. c. 1.]), Elmacin (Hist. Saracen, p. 88), Abulfeda (Annal. Moslem, p. 126), and Abulpharagius (Dynast, p. 130), the most satisfactory of the Arabs. i'*Our sure and indefatigable guide in the middle ages and Byzantine history, Charles du Fresne du Cange, has treated in several places of the Greek fire, and his collections leave few gleanings behind. Se^ particularly Glossar. Med. et Infim. Grascitat. p. 1275, sub voce uCp eaKa(j<riov vypav. Glossar. Med. et Infim. Latinitat. /^nis GrcBcus. Observations sur Villehardouin, p. 305, 306. Observations sur Joinville, p. 71, 72. [See below, note 22.] I'* Theophanes styles him ipxiTfVTwi' (p. 295 [a.m. 6165]). Cedrenus (p. 437 [i. p. 765]) brings this artist from (the ruins of) Heliopolis in Egypt ; and chemistry w;is indeed the peculiar science of the Egyptians,
