, converging at the city of Rome. One army was to advance from
Asia Minor and take Constantinople; another was to cross the Pyrenees
and overrun the territory of the Franks. Had the enterprise been
started at the time proposed there could have been little opposition
in the west, for the Franks were then busy fighting each other,
but luckily Muza fell into disgrace with the Caliph at this time
and his great project was undertaken by less able hands and on
a piecemeal plan.

The eastern line of invasion was undertaken first in the year 717.
A fleet of warships and transports to the number of 1800 sailed
to the Hellespont, carrying about 80,000 troops, while a great
army collected at Tarsus and marched overland toward the same
destination. Meanwhile two more fleets were being prepared in the
ports of Africa and Egypt, and a third army was being collected
to reenforce the first expedition. This army was to be under the
personal command of the Caliph himself. The third attack on the
Christian capital was intended to be the supreme effort.

Fortunately, the ruler of Constantinople at this hour of peril
was a man of ability and energy, Leo III; but the empire had sunk
so low as a result of the misrule of his predecessors that his
authority scarcely extended beyond the shores of the Sea of Marmora,
and his resources were at a low ebb. The navy on which so much
depended was brought to a high point of efficiency, but it was so
inferior in numbers to the Saracen armada that he dared not attempt
even a defense of the Dardanelles.

For the Arabs all went well at first. Unopposed they transported a
part of their army to the European shore, moved toward Constantinople
and invested it by land and sea. One detachment was sent to cover
Adrianople, which was occupied by a Christian garrison; the rest
of the force concentrated on the capital itself.

Meanwhile the Christian fleet lay anchored in the shelter of the
Golden Horn, protected by a boom of chains and logs. As the Saracen
ships came up to occupy the straits above the city they fell into
confusion in trying to stem the rapid current. Seeing his opportunity,
the emperor ordered the boom opened, and leading the way in his
flagship, he fell upon the huddle of Saracen vessels in the channel.
The latter could make little resistance, and before the main body of
the fleet could work up to the rescue, the Christians had destroyed
twenty and taken a number of prizes back to the Horn. A