Charles V, then, was the most powerful ruler alive, and the richest, thanks to the flow of gold and silver from the Indies. But, as Hugh Thomas shows in his narrative, his reign was at best a series of temporary triumphs, punctuated by misadventures. Much of the time he was at war, often in person. His most consistent enemy, Francis I of France, was heavily defeated, and captured, at the Battle of Pavia in 1525. But it did not prove decisive. He himself won the Battle of Mühlberg in 1547 to assert his supremacy in German territories. Titian, to crown the series of magnificent portraits he painted of the Emperor, did him on horseback in full armour, the first equestrian work of its kind. His Habsburg chin juts out defiantly over his glittering cuirass. But this victory too proved deceptive, and five years later Charles had to flee for his life from Germany, crossing the Brenner Pass in blinding rain. It was the same with his efforts to stem the Ottoman advance in the Mediterranean. In 1535, with the help of the greatest admiral of the day, Andrea Doria of Genoa, he landed a large expeditionary force and took Tunis. But a similar expedition to take Algiers in 1541, with 24,000 troops commanded by Cortés himself, ended in failure. 

Charles never seemed able to bring any of his incessant wars to a successful conclusion. Despite all his efforts, France remained an unsolved problem, both in north-west Europe and in Italy. Ottoman power remained a serious threat. The Emperor was never master of all Germany, and was unable to prevent the Reformation from spreading or to bring the Protestant princes to order. He could never feel easy about his authority in the Low Countries or even in Spain. There was always trouble somewhere, demanding his personal attention. 

That was the problem. Monarchy in Charles's day was still very much a personal vocation. Shakespeare's line "Uneasy lies the head that wears a crown" might have been written with Charles in mind — and he had several crowns, which multiplied the occasions of unease. He found it extremely difficult to delegate his authority, and so had to go himself. That meant he was never out of the saddle. When he finally decided to solve his unending problems by abdicating, handing over to his son Philip II and retiring to a monastery, he totted up his travels and complained he had been obliged to go ten times to Flanders, nine times to Germany, six to Spain, seven to Italy, four to France, twice to England, twice to Africa, plus various Mediterranean voyages. 

This cosmopolitan super-king never had a home. He was always squatting, palatially maybe, but in alien quarters. Hugh Thomas tells us that at Christmas 1546 he had slept in 40 different places since August. He had to transport great quantities of tapestry with him to keep out the draughts. He moved in the centre of a great inconvenient mob which limited the choice of resting-places. On his first arrival in Spain, for instance, Thomas says he had to bring with him 2,000 people and 1,000 horses. Moreover, despite all the bullion from the Indies, he seems often to have been short of money. Thomas quotes some of the contract he made with the Welsers, his German bankers from 1526. They were known as capitulationes, a good word. Then as now bankers seem to have been on top. The collateral for one was "the island of Venezuela". On the other hand, the bankers sometimes had to provide, in addition to cash, soldiers, sailors, ships and even skilled miners. Many of the documents and figures (Thomas provides some illuminating statistical appendices, as well as many excellent maps) suggest to me that Charles was often not on top of his administrative duties.