This is military history without much social or personal background. Its attractive virtue is nevertheless the absence of aridity. We do not learn in depth why armies and their commanders fought as they did but we are made continuously interested in what they tried to do and how. The decline of Byzantine power in Italy made of necessity a state of which the sovereign was the bishop of Rome. Who should be its defenders? And would those defenders claim secular sovereignty for themselves? In turn the heirs of Charlemagne, the German emperors, Normans from Sicily, French, Spaniards, Austrians, always from a distance and never satisfactorily, so that popes and cardinals scampered about amid Roman riots and bandit lords, and the bishops of Rome were forced to live as exiles, in Viterbo, or Anagni, or Avignon, or Florence, or Savona, or Gaeta. Probably the most secure time, before Vittorio Emanuele created an united Italy and so rescued the papacy for its spiritual mission, was the later Middle Ages and the early modern period, when popes did not shrink from enlisting their own armies, and climbed out of poverty by using force to secure prosperous lands. Pope Julius ii is notorious as a general but cardinals were the commonest form of commanders-in-chief; for the two reasons that they were the highest in the Vatican civil service, and could usually be trusted not to employ their military power in establishing private principalities. In addition, mercenary troops expressed a preference for serving under a general who was a cardinal, their army rose in reputation and when projectiles flew they liked to feel that the end for which they fought was the cause of God; privates respected their commander more, the enemy feared him more. This system met the difficulty that by church law no clergyman could shed blood. Not all cardinals were ordained. Those who were priests or bishops could plead that they killed no one, they only sent battalions into a campaign and if hired men like the Swiss were killed that was not their wish nor intention. To mercenaries the morality of a commander mattered little. On rare occasions a promising fighter, but unpromising ecclesiastic, might be made a cardinal to give him the required status. Cardinal Giovanni Vitelleschi, who died in 1440, had in him more than a streak of cruelty and was one of the most successful generals who fought in that troubled age among the Italian states. He established real order in central Italy by creating a military dictatorship which paid little regard to law or justice. He was not only a cardinal but the bishop of Recanati, the patriarch of Alexandria and the archbishop of Florence. Romans and others revered him as pater patriae, the saviour of his country, they put up a statue of him on the Capitol and there were those who said his cruelties were necessary and likened him to Romulus or the Emperor Augustus. Valla used the career of Vitelleschi as a peg to denounce the barbarity of government by priests: ‘To head a State is to be caught up in power politics’. There is an enchanting chapter on that civilised pope and warrior Pius ii whose feelings and motives we know something about because he enjoyed talking about himself. In his Commentaries he admired what Vitelleschi achieved for the Papal State: ‘it is proper that the army of the Church be commanded by a prelate, prudent and expert in what has to be done’. The casuistry about not shedding blood could hardly survive the criticism of Protestants or the Counter-Reformers, even though canonised Pope Pius v was a pope of that tradition on the use of force.