Excerpts From

CONSTANTINE PORPHYROGENITUS
DE ADMINISTRANDO IMPERIO

The following is taken from the 10th century work "De Administrando Imperio", a domestic policy manual written by the Byzantine emperor Constantine VII. Beginning in the 7th century, the Byzantine (eastern Roman) empire made wide use of a new weapon which they called the "Liquid Fire" or "Greek Fire".

From Wikipedia:

Greek fire was an incendiary weapon used by the Eastern Roman Empire beginning c. 672. Used to set fire to enemy ships, it consisted of a combustible compound emitted by a flame-throwing weapon. Some historians believe it could be ignited on contact with water, and was probably based on naphtha and quicklime. The Byzantines typically used it in naval battles to great effect, as it could continue burning while floating on water. The technological advantage it provided was responsible for many key Byzantine military victories, most notably the salvation of Constantinople from the first and second Arab sieges, thus securing the empire's survival.

The following pages are taken directly from the work of Constantine VII.  Here he instructs his son about the history of the Greek fire, and warns that it's composition must be kept a strict secret. Compare these words with the description of the second 'lamb-like' beast of Revelation 13:13:

And he doeth great wonders, so that he maketh fire come down from heaven on the earth in the sight of men (Revelation 13:13)

The following is taken from Edward Gibbon's History of the Decline and Fall of the Roman Empire:

In the two sieges, the deliverance of Constantinople may be chiefly ascribed to the novelty, the terrors, and the real efficacy of the Greek fire.⁶⁵⁷⁴ 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.⁶⁵⁷⁵ The skill of a chemist and engineer was equivalent to the succor of fleets and armies; and this discovery or improvement of the military art was fortunately reserved for the distressful period, when the degenerate Romans of the East were incapable of contending with the warlike enthusiasm and youthful vigor of the Saracens. The historian who presumes to analyze this extraordinary composition should suspect his own ignorance and that of his Byzantine guides, so prone to the marvellous, so careless, and, in this instance, so jealous of the truth. From their obscure, and perhaps fallacious, hints it should seem that the principal ingredient of the Greek fire was the naphtha,⁶⁵⁷⁶ or liquid bitumen, a light, tenacious, and inflammable oil,⁶⁵⁷⁷ which springs from the earth, and catches fire as soon as it comes in contact with the air. The naphtha was mingled, I know not by what methods or in what proportions, with sulphur and with the pitch that is extracted from evergreen firs.⁶⁵⁷⁸ From this mixture, which produced a thick smoke and a loud explosion, proceeded a fierce and obstinate flame, which not only rose in perpendicular ascent, but likewise burnt with equal vehemence in descent or lateral progress; instead of being extinguished, it was nourished and quickened by the element of water; and sand, urine, or vinegar, were the only remedies that could damp the fury of this powerful agent, which was justly denominated by the Greeks the liquid, or the maritime, fire. For the annoyance of the enemy, it was employed with equal effect, by sea and land, in battles or in sieges. It was either poured from the rampart in large boilers, or launched in red-hot balls of stone and iron, or darted in arrows and javelins, twisted round with flax and tow, which had deeply imbibed the inflammable oil; sometimes it was deposited in fire-ships, the victims and instruments of a more ample revenge, and was most commonly blown through long tubes of copper which were planted on the prow of a galley, and fancifully shaped into the mouths of savage monsters, that seemed to vomit a stream of liquid and consuming fire. This important art was preserved at Constantinople, as the palladium of the state: the galleys and artillery might occasionally be lent to the allies of Rome; but the composition of the Greek fire was concealed with the most jealous scruple, and the terror of the enemies was increased and prolonged by their ignorance and surprise. In the treaties of the administration of the empire, the royal author⁶⁵⁷⁹ suggests the answers and excuses that might best elude the indiscreet curiosity and importunate demands of the Barbarians. They should be told that the mystery of the Greek fire had been revealed by an angel to the first and greatest of the Constantines, with a sacred injunction, that this gift of Heaven, this peculiar blessing of the Romans, should never be communicated to any foreign nation; that the prince and the subject were alike bound to religious silence under the temporal and spiritual penalties of treason and sacrilege; and that the impious attempt would provoke the sudden and supernatural vengeance of the God of the Christians. By these precautions, the secret was confined, above four hundred years, to the Romans of the East; and at the end of the eleventh century, the Pisans, to whom every sea and every art were familiar, suffered the effects, without understanding the composition, of the Greek fire. It was at length either discovered or stolen by the Mohammedans; and, in the holy wars of Syria and Egypt, they retorted an invention, contrived against themselves, on the heads of the Christians. A knight, who despised the swords and lances of the Saracens, relates, with heartfelt sincerity, his own fears, and those of his companions, at the sight and sound of the mischievous engine that discharged a torrent of the Greek fire, the feu Gregeois, as it is styled by the more early of the French writers. It came flying through the air, says Joinville,⁶⁵⁸⁰ like a winged long-tailed dragon, about the thickness of a hogshead, with the report of thunder and the velocity of lightning; and the darkness of the night was dispelled by this deadly illumination. The use of the Greek, or, as it might now be called, of the Saracen fire, was continued to the middle of the fourteenth century,⁶⁵⁸¹ when the scientific or casual compound of nitre, sulphur, and charcoal, effected a new revolution in the art of war and the history of mankind⁶⁵⁸²

⁶⁵⁷⁴ 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. See particularly Glossar. Med. et Infim. Græcitat. p. 1275, sub voce. Πυρ θαλάσσιον, ὕγρον; Glossar. Med. et Infim. Latinitat. Ignis Grœcus. Observations sur Villehardouin, p. 305, 306. Observations sur Joinville, p. 71, 72.
 

⁶⁵⁷⁵ Theophanes styles him, άρχιτεκτών (p. 295 [t. i. p. 542, ed. Bonn]). Cedrenus (p. 437 [tom. i. p. 765, ed. Bonn]) brings this artist from (the ruins of) Heliopolis in Egypt; and chemistry was indeed the peculiar science of the Egyptians.
 

⁶⁵⁷⁶ The naphtha, the oleum incendiarium of the history of Jerusalem, (Gest. Dei per Francos, p. 1167), the Oriental fountain of James de Vitry, (l. iii. c. 84 [p. 1098]), is introduced on slight evidence and strong probability. Cinanmus (l. vi. p. 165 [c. 10, p. 283, ed. Bonn]) calls the Greek fire πῦρ Μήδικον: and the naphtha is known to abound between the Tigris and the Caspiân Sea. According to Pliny, (Hist. Natur. ii. 109), it was subservient to the revenge of Medea, and in either etymology the ἔλαιον Μηδίας, or Μηδείας (Procop. de Bell. Gothic. l. iv. c. 11), may fairly signify this liquid bitumen.
 

[Note: It is remarkable that the Syrian historian Michel gives the name of naphtha to the newly-invented Greek fire, which seems to indicate that this substance formed the base of the destructive compound. St. Martin, tom. xi. p. 420.—M.]
 

⁶⁵⁷⁷ On the different sorts of oils and bitumens, see Dr. Watson’s (the present bishop of Llandaff’s) Chemical Essays, vol. iii. essay i., a classic book, the best adapted to infuse the taste and knowledge of chemistry. The less perfect ideas of the ancients may be found in Strabo (Geograph. l. xvi. p. 1078) and Pliny, (Hist. Natur. ii. 108, 109). Huic (Naphthae) magna cognatio est ignium, transiliuntque protinus in eam undecunque visam. Of our travelers I am best pleased with Otter, (tom. i. p. 153, 158).
 

⁶⁵⁷⁸ Anna Comnena has partly drawn aside the curtain. Ἀπὸ τῆς πεύκης, καὶ ἄλλων τινῶν τοιούτων δένδρων ἀειθάλων θυνἀγεται δακρυον ἄκαυστον. Τοῦτο μετὰ θείον τριβόυμενον ὲμβάλλεται εἰς αὐλίσκους καλάμων, καὶ ἐμφύσαται παρὰ τοῦ παίζοντος λάβρῳ καὶ συνεχεῖ πνεν́ματι (Alexiad. l. xiii. p. 383). Elsewhere (l. xi. p. 336) she mentions the property of burning, κατὰ τὸ πρανὲς καὶ ἐφ᾽ ἑκάτερα. Leo, in the xixth chapter [§ 51] of his Tactics, (Opera Meursii, tom. vi. p. 843, edit. Lami, Florent. 1745), speaks of the new invention of πῦρ μετὰ βροντῆς καὶ κάπνου. These are genuine and Imperial testimonies.
 

⁶⁵⁷⁹ Constantin. Porphyrogenit. de Administrat. Imperii, c. xiii. p. 64, 65 [ed. Par.; tom. iii. p. 84, sq., ed. Bonn].
 

⁶⁵⁸⁰ Histoire de St. Louis, p. 39. Paris, 1668, p. 44. Paris, de l’Imprimerie Royale, 1761. The former of these editions is precious for the observations of Ducange; the latter for the pure and original text of Joinville. We must have recourse to that text to discover, that the feu Gregeois was shot with a pile or javelin, from an engine that acted like a sling.
 

⁶⁵⁸¹ The vanity, or envy, of shaking the established property of Fame, has tempted some moderns to carry gunpowder above the 14th, (see Sir William Temple, Dutens, etc.), and the Greek fire above the viith century, (see the Saluste du Président des Brosses, tom. ii. p. 381). But their evidence, which precedes the vulgar era of the invention, is seldom clear or satisfactory, and subsequent writers may be suspected of fraud or credulity. In the earliest sieges, some combustibles of oil and sulphur have been used, and the Greek fire has some affinities with gunpowder both in its nature and effects: for the antiquity of the first, a passage of Procopius, (de Bell. Goth. l. iv. c. 11 [t. ii. p. 512, ed. Bonn]); for that of the second, some facts in the Arabic history of Spain, (a.d. 1249, 1312, 1332. Bibliot. Arab. Hisp. tom. ii. p. 6, 7, 8), are the most difficult to elude.
 

⁶⁵⁸² That extraordinary man, Friar Bacon, reveals two of the ingredients, saltpetre and sulphur, and conceals the third in a sentence of mysterious gibberish, as if he dreaded the consequences of his own discovery, (Biog. Brit. vol. i. p. 430, new edition.)
 

Gibbon, E. (2004). The history of the decline and fall of the Roman Empire (H. H. Milman, Ed.).