What spurred Gustavus to the great battle to be described was the capture by Tilly on May 20, 1631, of the city of Magdeburg, and the massacre of its thirty thousand citizens, men, women, and children. From this scene of frightful outrage and destruction Tilly failed to call off his men until the city lay in ruins and its people in death. A tall, haggard, grim warrior, hollow-cheeked, and wild-looking, with large bright eyes under his shaggy brows, Tilly looked capable of the deeds of ferocity with which the world credited him. [Illustration: STATUE OF GUSTAVUS ADOLPHUS.] While all Christendom shuddered with horror at the savage slaughter at Magdeburg, the triumphant Tilly marched upon and captured the city of Leipsic. Here he fixed his headquarters in the house of a grave-digger, where he grew pale at seeing the death's-head and cross-bones with which the owner had decorated his walls. These significant emblems may have had something to do with the unusual mildness with which he treated the citizens of that town. The cause of Protestantism in Germany was now in serious jeopardy and Gustavus felt that the time had come to strike a hard blow in its behalf. The elector of Saxony, who had hitherto stood aloof, now came to his aid with an army of eighteen thousand men, and it was resolved to attack Tilly at once, before the reinforcements on the way to join him could arrive. These statements are needful, to show the momentous import of the great battle of September 7, 1631. In the early morning of that day the two armies came face to face, Tilly having taken a strong and advantageous position not far from Leipsic, where he hoped to avoid a battle. But he was obliged, when the enemy began to move upon him, to alter his plans and move towards the hills on his left. At the foot of these his army was drawn up in a long line, with the artillery on the heights beyond, where it would sweep the extensive plain of Breitenfeld in his front. Over this plain the Swedes and Saxons advanced in two columns, towards a small stream named the Lober, which ran in Tilly's front. To prevent this crossing Pappenheim had early moved at the head of two thousand cuirassiers, a movement which Tilly reluctantly permitted, though strictly ordering him not to fight. Disregarding this order Pappenheim charged the vanguard of the Swedes, only to find that he had met an impregnable line and to be driven back in disorder. To check pursuit he set fire to a village at the crossing-point, but this had no effect upon the movement of the advancing troops nor his own disorderly retreat.