To a man of Frederick’s haughty temperament there was but one absolution he could win for this crime, so to master Rome that he could squeeze her judgements to his fancy like a sponge between his strong fingers. ‘Italy is my heritage,’ he wrote to the Pope, ‘and all the world knows it.’

In his passionate determination to obtain this heritage statesmanship was thrown to the winds. He had planned a strong monarchy in Naples, but in Germany he undermined the foundations of royal authority that Barbarossa and Henry VI had begun to lay. ‘Let every Prince’, he declared, ‘enjoy in peace, according to the improved custom of his land, his immunities, jurisdictions, counties and hundreds, both those which belong to him in full right, and those which have been granted out to him in fief.’

The Italian Hohenstaufen only sought from his northern kingdom, whose good government he thus carelessly sacrificed to feudal anarchy, sufficient money to pay for his campaigns beyond the Alps and leisure to pursue them. In the words of a modern historian, ‘he bartered his German kingship for an immediate triumph over his hated foe.’

At first victory rewarded his energy and skill. His hereditary enemy, the ‘Lombard League’, had tampered with the loyalty of his eldest son, Henry, King of the Romans, whom he had left to rule in Germany: but Frederick discovered the plot in time and deposed and imprisoned the culprit. In despair at the prospect of lifelong imprisonment held out to him, the young Henry flung himself to his death down a steep mountain-side; and Conrad, his younger brother, a boy of eight, was crowned in his stead.

In North Italy Frederick pursued the policy not so much of trampling down resistance with his German levies, like his grandfather Barbarossa, as of employing Italian nobles of the Ghibelline party, whom he supported and financed that they might fight his battles and make his wrath terrible in the popular hearing. Such were Eccelin de Romano and his brother Alberigo, lords of Verona and Vicenza, whose tyranny and cruelties seemed abnormal even in their day.

‘The Devil’s own Servant’ Eccelin is called by a contemporary, who describes how he slaughtered in cold blood eleven thousand prisoners.

‘I believe, in truth, no such wicked man has been from the beginning of the world unto our own days: for all men trembled at him as a rush quivers in the water ... he who lived to-day was not sure of the morrow, the father would seek out and slay his son, and the son his father or any of his kinsfolk to please this man.’

Alberigo ‘hanged twenty-five of the greatest men of Treviso who had in no wise offended or harmed him’; and as the prisoners struggled in their death agonies he thrust among their feet their wives, daughters, and sisters, whom he afterwards turned adrift half-naked to seek protection where they might.

Revenge when this ‘Limb of Satan’ fell into the hands of his enemies was of a brutality to match; for Alberigo and his young sons were torn in pieces by an infuriated mob, his wife and daughters burned alive, ‘though they were noble maidens and the fairest in the world and guiltless.’

Passions ran too deep between Guelf and Ghibelline to distinguish innocency, or to spare youth or sex. Cruelty, the most despicable and infectious of vices, was the very atmosphere of the thirteenth century, desecrating what has been described from another aspect as ‘an age of high ideals and heroic lives’.