It happened strangely enough that just while their ruin was preparing, the house of Swabia gained over their ecclesiastical foes what seemed likely to prove an advantage of the first moment. The son and successor of Barbarossa was Henry VI, a man who had inherited all his father's harshness with none of his father's generosity. By his marriage with Constance, the heiress of the Norman kings, he had become master of Naples and Sicily. Emboldened by the possession of what had been hitherto the stronghold of his predecessors' bitterest enemies, and able to threaten the Pope from south as well as north, Henry conceived a scheme which might have wonderfully changed the history of Germany and Italy. He proposed to the Teutonic magnates to lighten their burdens by uniting these newly-acquired countries to the Empire, to turn their feudal lands into allodial, and to make no further demands for money on the clergy, on condition that they should pronounce the crown hereditary in his family. Results of the highest importance would have followed this change, which Henry advocated by setting forth the perils of interregna, and which he doubtless meant to be but part of an entirely new system of polity. Already so strong in Germany, and with an absolute command of their new kingdom, the Hohenstaufen might have dispensed with the renounced feudal services, and built up a firm centralized system, like that which was already beginning to develope itself in France. First, however, the Saxon princes, then some ecclesiastics headed by Conrad of Mentz, opposed the scheme; the pontiff retracted his consent, and Henry had to content himself with getting his infant son Frederick the Second chosen king of the Romans. On Henry's untimely death the election was set aside, and the contest which followed between Otto of Brunswick and Philip of Hohenstaufen, brother of Henry the Sixth, gave the Popedom, now guided by the genius of Innocent the Third, an opportunity of extending its sway at the expense of its antagonist. The Pope moved heaven and earth on behalf of Otto, whose family had been the constant rivals of the Hohenstaufen, and who was himself willing to promise all that Innocent required; but Philip's personal merits and the vast possessions of his house gave him while he lived the ascendancy in Germany. His death by the hand of an assassin, while it seemed to vindicate the Pope's choice, left the Swabian party without a head, and the Papal nominee was soon recognized over the whole Empire. But Otto IV became less submissive as he felt his throne more secure. If he was a Guelf by birth, his acts in Italy, whither he had gone to receive the imperial crown, were those of a Ghibeline, anxious to reclaim the rights he had but just forsworn. The Roman Church at last deposed and excommunicated her ungrateful son, and Innocent rejoiced in a second successful assertion of pontifical supremacy, when Otto was dethroned by the youthful Frederick the Second, whom a tragic irony sent into the field of politics as the champion of the Holy See, whose hatred was to embitter his life and extinguish his house.