In Italy, his chief concern was to concentrate the southern States under his lead and form a military bulwark against the northerners. The Roman militia was strengthened: the petty princes of Benevento and Capua were persuaded that their shrunken territories were safer from the aggressions of Robert Guiscard if they paid allegiance to St. Peter: Mathilda of Tuscany did not even need to be persuaded to hold her troops at his disposal. It would be safe to say that Italy alone would have wrecked Gregory's policy but for the lucky accident of Tuscany passing to the pious Mathilda. She clung to Gregory so tenaciously that his opponents affected to see a scandal in the association. The chief thorn in his side was Robert Guiscard, who had founded a kingdom in southern Italy and refused to do homage. He laid waste the territory of the Pope's allies, and smiled at the anathema put on him. Gregory, as usual, turned to the sword. The Eastern Emperor had asked aid against the Turks, and Gregory summoned all Christian princes to contribute troops. He would lead the army in person, he said: supported by the aged Beatrice and the tender Mathilda. The northern princes smiled, and the plan of a crusade came to naught. But it was not merely concern for Constantinople which made Gregory dangerously ill when his plan miscarried. Historians generally overlook his letter to William of Burgundy,[213] in which he plainly states that he wants the troops for the purpose of intimidating--if not conquering--Robert: "perhaps," he says, they may afterwards proceed to the East. He was still more irritated when Robert himself entered into an alliance with Constantinople. Gregory angrily wrote to ask the King of Denmark to send his son with an army and wrest the south of Italy from the "vile heretics" who held it.[214] He was similarly thwarted in nearly every country in Europe, and his anathemas were terrible to hear. I have already referred to his haughty language to Lanfranc, yet the English bishops continued, year after year, to ignore the imperious summons to attend his Roman synods. In 1079 Gregory wrote to Lanfranc that he understood that the King prevented them from coming, and was surprised that the "superstitious love" or fear of any man should come between him and his duty.[215] Lanfranc still evaded, almost fooled, him, and, when Gregory threatened to suspend him, affected to be engaged in examining the claims of an Anti-Pope whom Henry IV. had set up. With William himself Gregory was bitterly disappointed. When, in 1080, he ordered the King to collect the arrears of Peter's Pence and acknowledge his feudal obligations to Rome, William somewhat contemptuously replied that he would forward the money, but would pay allegiance to no man. Gregory was so angry that he told his legates that the money was no use without the "honour."[216]