ially
Constantinople, its capital, passed through many vicissitudes; but the
sack of the city by Alexius Commenus, the founder of the line, was
remembered by the populace to the disadvantage of all his successors;
the last of whom, Andronicus I, ended his reign in 1185. John, the son
of Alexius [1118-1143], ruled with discretion and ability, and recovered
some territory from the Turks.

Manuel I, the son of John [1143-1181], ruled during a period of almost
constant war, and for a time he held the enemies of the empire in check.
But he appears to have been more endowed with courage and the spirit of
enterprise than with good judgment, and his conduct of the empire
coincided with events that, as seen in history, contributed to its
decline, which after his death followed rapidly. As this decline is to
be dated especially from the passing but not ineffectual invasion of
Roger II, King of Sicily, in 1146, some account of that, together with a
view of conditions immediately preceding, becomes important in a work
like this.

The century and a half before Roger's invasion had been a period of
tranquillity for the distinctively Greek people of the empire, who had
increased rapidly in numbers and wealth, and were in possession of an
extensive commerce and many manufactures. Therefore they were perhaps
the greatest sufferers from the adverse events which befell the State.)

The emperor Alexius I had concluded a commercial treaty with Pisa toward
the end of his reign. Manuel renewed this alliance, and he appears to
have been the first of the Byzantine emperors who concluded a public
treaty with Genoa. The pride of the emperors of the Romans--as the
sovereigns of Constantinople were styled--induced them to treat the
Italian republics as municipalities still dependent on the Empire of the
Caesars, of which they had once formed a part; and the rulers both of
Pisa and Genoa yielded to this assumption of supremacy, and consented to
appear as vassals and liegemen of the Byzantine emperors, in order to
participate in the profits which they saw the Venetians gained by
trading in their dominions.

Several commercial treaties with Pisa and Genoa, as well as with Venice,
have been preserved. The obligations of the republics are embodied in
the charter enumerating the concessions granted by the Emperor, and the
document is called a _chrysobulum_, or golden bull, from the golden seal
of the Emperor attached to it as the certificate of its