A CRIMINAL HISTORY OF MANKIND

obligations. So the new Caliph had to go to war. It was a political as well as a religious decision; if
Arabia was allowed to split apart again, it would lose its strength. If it lost its strength, then it was
no longer an effective force for conquest. And if it ceased to conquer, then there would be no flow
of booty back to Mecca and Medina. So there was a bitter struggle that lasted for two years, until
the rebel tribes were finally brought to heel. Then Abu Bekr died and was succeeded by another
close associate of the prophet, Omar. He was faced with the same alternative: expand or stagnate.
He had no hesitation about throwing his energies into expansion.
The obvious enemy was the ‘unbeliever’ - in this case, Rome and Persia. And these two empires
were exhausted by war. Omar’s great general, Khalid, known as ‘the Sword of Allah’, defeated the
Byzantines near Damascus and took Syria in 635. Jerusalem fell three years later. Iraq - occupied
by the Persians - fell in 637, Mesopotamia in 641, Egypt in 642. And after a struggle of sixteen
years, Persia itself fell to the Muslims. The citizens of most of the conquered lands welcomed the
Arabs; they were tired of paying taxes to a ruler in a distant city; the Arabs at least were
neighbours. Their conquest of Alexandria, and its subsequent loss when a Byzantine fleet appeared
on the horizon, made the Arabs aware that they also needed ships. So they built their own fleet, and
in 655 annihilated the Byzantine fleet.
Now only one major stronghold remained: Constantinople itself. In 673, the Arabian fleet
blockaded Constantinople. The walls built by Constantine and his successors proved impregnable,
so the Arabs prepared to wait until they had starved the city into submission. Its fall seemed
inevitable.
And at this point, a single invention altered the tide of history. It was the brainchild of an architect
named Callinicus, who came from Heliopolis, in Syria. He had decided that he preferred the
Christian Emperor to the Muslim Caliph, and moved to Constantinople - now ruled by Constantine
IV. Callinicus seems to have been interested in chemistry, and in explosives. He discovered that a
mixture of saltpetre, bitumen, naphtha, sulphur and quicklime could produce a flame that was
almost unquenchable. The secret formula is now lost, but it seems clear that the naphtha, bitumen
and sulphur were the inflammables, while the saltpetre provided the oxygen to keep it burning.
When water is added to quicklime (calcium oxide), the result is immense heat. This seems to have
been the basic secret of the substance that became known as ‘Greek fire’. The startled Arabs found
themselves facing ships that came towards them belching fire like dragons. When the fire landed on
the water, it went on burning. It could be hurled through the air with catapults, in the form of balls
of flax soaked in the chemical, or it could be made to roar from a copper or iron tube like a
flamethrower. If Callinicus had stayed in Syria and given his invention to the Caliph, the Arabs
would have been invincible. Now the Byzantines used it to scatter the Arab fleet. Men who were
struck by the flames writhed in agony as their flesh bubbled and melted. When Greek fire landed on
wooden decks, it burned its way through them; water only made it seethe and spit more violently.
Gibbon says it could be extinguished by urine, but it is doubtful whether any Arab kept his head
enough to try that interesting remedy.
The Arab navies continued returning for five years, but they never learned the secret of Greek fire.
And so long as Constantinople could obtain its supplies by sea, it was impregnable. It would be
several more centuries before the invention of gunpowder and cannons made the city wall obsolete.
So the Arabs retired from the fray, and in 677 A.D., the Byzantine navy destroyed the Arab fleet at
Syllaeum. All Europe heaved a sigh of relief; for it had seemed by this time that the Arabs were
unconquerable, and tales of their massacres had terrified everybody. (These were mostly