Against the advice of his wisest captains Alexius resolved to risk the event of a general action. The princess Anna, who drops a tear on this melancholy event, is reduced to praise the strength and swiftness of her father’s horse, and his vigorous struggle when he was almost overthrown by the stroke of a lance which had shivered the imperial helmet. His desperate valour broke through a squadron of Franks who opposed his flight; and, after wandering two days and as many nights in the mountains, he found some repose of body, though not of mind, in the walls of Lychnidus. The victorious Robert reproached the tardy and feeble pursuit which had suffered the escape of so illustrious a prize; but he consoled his disappointment by the trophies and standards of the field, the wealth and luxury of the Byzantine camp, and the glory of defeating an army five times more numerous than his own.

A Venetian noble sold the city for a rich and honourable marriage. At the dead of night several rope-ladders were dropped from the walls, the light Calabrians ascended in silence, and the Greeks were awakened by the name and trumpets of the conqueror. Yet they defended the street three days against an enemy already master of the rampart; and near seven months elapsed between the first investment and the final surrender of the place. From Durazzo the Norman duke advanced into the heart of Epirus or Albania, traversed the first mountains of Thessaly, surprised three hundred English in the city of Castoria, approached Thessalonica, and made Constantinople tremble.

A more pressing duty suspended the prosecution of his ambitious designs. By shipwreck, pestilence, and the sword his army was reduced to a third of the original numbers; and instead of being recruited from Italy, he was informed, by plaintive epistles, of the mischiefs and dangers which had been produced by his absence; the revolt of the cities and barons of Apulia, the distress of the pope, and the approach or invasion of Henry, king of Germany. Highly presuming that his person was sufficient for the public safety, he repassed the sea in a single brigantine, and left the remains of the army under the command of his son and the Norman counts, exhorting Bohemond to respect the freedom of his peers, and the counts to obey the authority of their leader. The son of Guiscard trod in the footsteps of his father; and the two destroyers are compared, by the Greeks, to the caterpillar and the locust, the last of whom devours whatever has escaped the teeth of the former.

After winning two battles against the emperor, he descended into the plain of Thessaly, and besieged Larissa, the fabulous realm of Achilles, which contained the treasure and magazines of the Byzantine camp. The courage of Bohemond was always conspicuous, and often successful; but his camp was pillaged by a stratagem of the Greeks; the city was impregnable; and the venal or discontented counts deserted his standard, betrayed their trusts, and enlisted in the service of the emperor. Alexius returned to Constantinople with the advantage, rather than the honour, of victory. After evacuating the conquests which he could no longer defend, the son of Guiscard embarked for Italy, and was embraced by a father who esteemed his merit, and sympathised in his misfortune.

Of the Latin princes, the allies of Alexius and enemies of Robert, the most prompt and powerful was Henry IV, king of Germany and Italy, and future emperor of the West. Henry was the severe adversary of the Normans, the allies and vassals of Gregory VII, his implacable foe. The long quarrel of the throne and mitre had been recently kindled by the zeal and ambition of that haughty priest; the king and the pope had degraded each other, and each had seated a rival on the temporal or spiritual throne of his antagonist. After the defeat and death of his Swabian rebel, Henry descended into Italy, to assume the imperial crown, and to drive from the Vatican the tyrant of the church. But the Roman people adhered to the cause of Gregory; their resolution was fortified by supplies of men and money from Apulia; and the city was thrice ineffectually besieged by the king of Germany.

In the fourth year he corrupted, it is said, with Byzantine gold, the nobles of Rome, whose estates and castles had been ruined by the war. The gates, the bridges, and fifty hostages, were delivered into his hands; the anti-pope, Clement III, was consecrated in the Lateran; the grateful pontiff crowned his protector in the Vatican; and the Emperor Henry fixed his residence in the capitol, as the lawful successor of Augustus and Charlemagne. The ruins of the Septizonium were still defended by the nephew of Gregory; the pope himself was invested in the castle of St. Angelo; and his last hope was in the courage and fidelity of his Norman vassal. Their friendship had been interrupted by some reciprocal injuries and complaints; but, on this pressing occasion, Guiscard was urged by the obligation of his oath, by his interest, more potent than oaths, by the love of fame, and his enmity to the two emperors. Unfurling the holy banner, he resolved to fly to the relief of the prince of the apostles; the most numerous of his armies, six thousand horse, and thirty thousand foot, was instantly assembled; and his march from Salerno to Rome was animated by the public applause and the promise of the divine favour.

Henry, invincible in sixty-six battles, trembled at his approach; recollected some indispensable affairs that required his presence in Lombardy; exhorted the Romans to persevere in their allegiance; and hastily retreated three days before the entrance of the Normans. In less than three years, the son of Tancred de Hauteville enjoyed the glory of delivering the pope, and of compelling the two emperors, of the East and the West, to fly before his victorious arms.

But the triumph of Robert was clouded by the calamities of Rome. By the aid of the friends of Gregory, the walls had been perforated or scaled; but the imperial faction was still powerful and active; on the third day, the people rose in a furious tumult; and a hasty word of the conqueror, in his defence or revenge, was the signal of fire and pillage. The Saracens of Sicily, the subjects of Roger, and auxiliaries of his brother, embraced this fair occasion of rifling and profaning the Holy City of the Christians; many thousands of the citizens, in the sight, and by the allies, of their spiritual father, were exposed to violation, captivity, or death; and a spacious quarter of the city, from the Lateran to the Colosseum, was consumed by the flames.

The deliverer and scourge of Rome might have indulged himself in a season of repose; but in the same year of the flight of the German emperor, the indefatigable Robert resumed the design of his eastern conquests. The zeal or gratitude of Gregory had promised to his valour the kingdom of Greece and Asia; his troops were assembled in arms, flushed with success and eager for action. By the union of the Greeks and Venetians, the Adriatic was covered with a hostile fleet. The dominion of the sea was disputed in three engagements, in sight of the Island of Corfu; in the two former, the skill and number of the allies were superior; but in the third, the Normans obtained a final and complete victory. The winter season suspended his progress; with the return of spring he again aspired to the conquest of Constantinople; but, instead of traversing the hills of Epirus, he turned his arms against Greece and the islands, where the spoils would repay the labour, and where the land and sea forces might pursue their joint operations with vigour and effect.