Meantime, however, the Thirty Years' War had begun. Frederick's general, Mansfeld, held out for him in the Palatinate; the dissolution of the army of the Protestant Union supplied him with fresh soldiers, content to live by plunder; English volunteers and new German allies joined; and the struggle went from bad to worse. The failure or defeat of the first Protestant combatants brought others upon the scene; James of England appealed to Gustavus Adolphus of Sweden and Christian IV of Denmark to join him in recovering the Palatinate for his son-in-law, and, unable to subsidize Gustavus as he required, made terms with Christian, who at once entered the war. Thereupon the emperor employed Wallenstein, and the Protestants were defeated and hard pressed, till the great Gustavus came to their aid. Under his masterly leadership they regained their ground, but could not decisively triumph. After his death at the battle of Lützen (1632) new developments took place, France entering the imbroglio by way of weakening her enemies Austria and Spain, the two pillars of the empire; and one period of war passed into another without stay or respite. In the course of this inconceivable struggle children grew to middle age, and men grew from youth to grey hairs; most of those who began the strife passed away ere it had ended; the French Richelieu rose to greatness and died; and the English Civil War passed through nearly its whole course, a mere episode in comparison. When at length there was signed the Peace of Westphalia (1648) the German world was reduced to mortal exhaustion. The armies on both sides had been to the common people as the monstrous dragons of fable, bestial devourers, dealing ruin to friend and foe alike. Every sack of a city was a new triumph of cruelty and wickedness; tortures were inflicted by the mercenaries which almost redeemed the name of the Inquisition; and, as of old in the Ireland of Elizabeth's day, peasants were found dead with grass in their mouths. According to some calculations, half of the entire population of Germany was gone; and it is certain that in many districts numbers and wealth, man and beast, had been reduced in a much greater proportion, whole provinces being denuded of live stock, and whole towns going to ruin. German civilization had been thrown back a full hundred years, morally and materially. No such procession of brutality and vice as followed the armies of Tilly and Wallenstein had been seen since the first Crusade; and the generation which had seen them and been able to survive them was itself grown callous. Capacity, culture, and conduct had alike fallen below the levels of a century before.