The King of Sweden bound himself to furnish soldiers,—­thirty thousand men at the least; France was to pay, by way of subsidy, four hundred thousand crowns a year, and to give a hundred thousand crowns to cover past expenses.  Gustavus Adolphus promised to maintain the existing religion in such countries as he might conquer, “though he said, laughingly, that there was no possibility of promising about that, except in the fashion of him who sold the bear’s skin;” he likewise guaranteed neutrality to the princes of the Catholic league, provided that they observed it towards him.  The treaty was made public at once, through the exertions of Gustavus Adolphus, though Cardinal Richelieu had charged Charnace to keep it secret for a time.

Torquato Conti, one of the emperor’s generals, who had taken Wallenstein’s place, wished to break off warfare during the long frosts.  “My men do not recognize winter,” answered Gustavus Adolphus.  “This prince, who did not take to war as a pastime, but made it in order to conquer,” marched with giant strides across Germany, reducing everything as he went.  He had arrived, by the end of April, before Frankfurt-on-the Oder, which he took; and he was preparing to succor Magdeburg, which had early pronounced for him, and which Tilly, the emperor’s general, kept besieged.  The Elector of Saxony hesitated to take sides; he refused Gustavus Adolphus a passage over the bridge of Dessau, on the Elbe.  On the 20th of May Magdeburg fell, and Tilly gave over the place to the soldiery; thirty thousand persons were massacred, and the houses committed to the flames.  “Nothing like it has been seen since the taking of Troy and of Jerusalem,” said Tilly in his savage joy.  The Protestant princes, who had just been reconstituting the Evangelical Union, in the diet they had held in February at Leipzig, revolted openly, ordering levies of soldiers to protect their territories; the Catholic League, renouncing neutrality, flew to arms on their side; the question became nothing less than that of restoring to the Protestants all that had been granted them by the peace of Passau.  The soldiery of Tilly were already let loose on electoral Saxony; the elector, constrained by necessity, intrusted his soldiers to Gustavus Adolphus, who had just received re-enforcements from Sweden, and the king marched against Tilly, still encamped before Leipzig, which he had forced to capitulate.

The Saxons gave way at the first shock of the imperial troops, but the King of Sweden had dashed forward, and nothing could withstand him; Tilly himself, hitherto proof against lead and steel, fell wounded in three places; five thousand dead were left on the field of battle; and Gustavus Adolphus dragged at his heels seven thousand prisoners.  “Never did the grace of God pull me out of so bad a scrape,” said the conqueror.  He halted some time at Mayence, which had just opened its gates to him.  Axel Oxenstiern, his most faithful servant and oldest friend,