Gustavus Adolphus has been blamed, especially by the admirers and defenders of the houses of Brandenburg and Saxony, for not having saved Magdeburg. This he might have done, had he disregarded the neutrality asserted by John George; but he had been bitterly disappointed at his reception by the Protestant princes, he could not trust them, and was not strong enough to fight Tilly with possible enemies in his rear. In fact, George William of Brandenburg immediately ordered him to give up Spandau and leave his territory. Then Gustavus did what he should have done at first: he planted his cannon before Berlin, and threatened to lay the city in ashes. This brought George William to his senses; he agreed that his fortresses should be used by the Swedes, and contributed 30,000 dollars a month towards the expenses of the war. So many recruits flocked to the Swedish standard that both Mecklenburgs were soon cleared of the Imperial troops, the banished Dukes restored, and an attack by Tilly upon the fortified camp of Gustavus was repulsed with heavy losses. [Sidenote: 1631. DEFEAT OF TILLY.] Landgrave William of Hesse Cassel was the first Protestant prince who voluntarily allied himself with the Swedish king. He was shortly followed by the unwilling but helpless John George of Saxony, whose territory was invaded and wasted by Tilly's army. Ferdinand II. had given this order, meaning that the Elector should at least support his troops. Tilly took possession of Halle, Naumburg and other cities, plundered and levied heavy contributions, and at last entered Leipzig, after bombarding it for four days. Then John George united his troops with those of Gustavus Adolphus, who now commanded an army of 35,000 men. Tilly and Pappenheim had an equal force to oppose him. After a good deal of cautious manoeuvring, the two armies stood face to face near Leipzig, on the 17th of September, 1631. The Swedes were without armor, and Gustavus distributed musketeers among the cavalry and pikemen. Banner, one of his generals, commanded his right, and Marshal Horn his left, where the Saxons were stationed. The army of Tilly was drawn up in a long line, and the troops wore heavy cuirasses and helmets: Pappenheim commanded the left, opposite Gustavus, while Tilly undertook to engage the Saxons. The battle-cry of the Protestants was "God with us!"--that of the Catholics "Jesu Maria!" Gustavus, wearing a white hat and green feather, and mounted on a white horse, rode up and down the lines, encouraging his men. The Saxons gave way before Tilly, and began to fly; but the Swedes, after repelling seven charges of Pappenheim's cavalry, broke the enemy's right wing, captured the cannon and turned them against Tilly. The Imperial army, thrown into confusion, fled in disorder, pursued by the Swedes, who cut them down until night put an end to the slaughter. Tilly, severely wounded, narrowly escaped death, and reached Halle with only a few hundred men. [Sidenote: 1632.]