In September 1517 he arrived in Spain, a country with whose customs he was unfamiliar and whose language he was as yet barely able to speak.
There he instituted, under Burgundian influence, a government that was little better than foreign rule.
As in 1532, when Charles had faced the Ottoman Turks before Vienna, neither side cared to open hostilities, with the result that the did not open until December 1545, but Paul III had earlier offered Charles men and money against the heretics.
When the Protestant princes failed to put in an appearance at the imperial Diet of Regensburg in 1546, the religious and political situation turned critical once again. In a battle that decided the whole campaign and placed his archenemies at his mercy, the emperor (who had been attacked by the German princes the previous September) defeated the Protestants at in April 1547.
In 1516 Spain’s floating debt amounted to 20,000 livres; by 1556 it had risen to 7,000,000. Thus, the campaign of 1543–44, inadequately financed, bogged down.
It was to no avail that the French and imperial armies faced one another in the field in November 1543 and again in August 1544.
The newly started war between the emperor and France also came to a close when the mother of Francis I approached .
Faced with renewed Turkish onslaughts, the emperor granted some concessions in return for armed support against the enemy.
Charles’s attempt to retake Metz that fall ended in a complete fiasco, with Burgundy capitulating to Valois and the emperor defeated in his struggle for hegemony in western Europe.With it, he rejected Luther’s doctrines and essentially declared war on Protestantism. Even though he granted an amnesty, the young monarch proved to be an intransigent ruler, bloodily suppressing the revolt and signing 270 death warrants.Those actions were nevertheless followed by a rapid and complete rapprochement between the pacified people and their sovereign; in fact, it was during that second and protracted sojourn in Spain (1522–29) that Charles became a Spaniard, with Castilian grandees replacing the Burgundians.There soon developed an emotionally tinged understanding between Charles and his Spanish subjects that was to be steadily deepened during his long rule.Henceforth, it was primarily the material resources of his Spanish domains that sustained his far-flung policies and his Spanish troops who acquitted themselves most bravely and successfully in his wars.