His first movement, now, was against the Pope. He crossed the Alps with a large army, was crowned King of Lombardy, and then marched towards Rome. Gregory's only friend was the Countess Matilda of Tuscany, who resisted Henry's advance until the cities of Pisa and Lucca espoused his cause. Then he laid siege to Rome, and a long war began, during which the ancient city suffered more than it had endured for centuries. The end of the struggle was a devastation worse than that inflicted by Geiserich. When Henry finally gained possession of the city, and the Pope was besieged in the castle of St. Angelo, the latter released Robert Guiscard, chief of the Normans in Southern Italy, from the ban of excommunication which he had pronounced against him, and called him to his aid. A Norman army, numbering 36,000 men, mostly Saracens, approached Rome, and Henry was compelled to retreat. The Pope was released, but his allies burned all the city between the Lateran and the Coliseum, slaughtered thousands of the inhabitants, carried away thousands as slaves, and left a desert of blood and ruin behind them. Gregory VII. did not dare to remain in Rome after their departure: he accompanied them to Salerno, and there died in exile, in 1085. Henry IV. immediately appointed a new Pope, Clement III., by whom he was crowned Emperor in St. Peter's. After Gregory's death, the Normans and the French selected another Pope, Urban II., and until both died, fifteen years afterwards, they and their partisans never ceased fighting. The Emperor Henry, however, who returned to Germany immediately alter his coronation, took little part in this quarrel. The last twenty years of his reign were full of trouble and misfortune. His eldest son, Konrad, who had lived mostly in Lombardy, was in 1092 persuaded to claim the crown of Italy, was acknowledged by the hostile Pope, and allied himself with his father's enemies. For a time he was very successful, but the movement gradually failed, and he ended his days in prison, in 1101. [Sidenote: 1105. TREACHERY OF HENRY IV.'S SON.]