Hopeless of victory the Imperialist centre was giving way, when the explosion of one of their powder wagons still further shook them. Attacked on both flanks and in front the Imperialist centre wavered, and in a few minutes would have been in full flight. The Swedish victory seemed assured, when a mighty trampling of horse was heard, and emerging from the smoke Pappenheim with eight regiments of Imperial cavalry dashed into the fray.
Pappenheim had already captured the citadel of Halle when Wallenstein's messenger reached him. To wait until his infantry, who were engaged in plundering, could be collected, and then to proceed at their pace to the field of battle, would be to arrive too late to be of service, and Pappenheim instantly placed himself at the head of his eight regiments of magnificent cavalry, and galloped at full speed to the battlefield eighteen miles distant. On the way he met large numbers of flying Poles and Croats, the remnants of the Austrian left, who had been driven from the field by Gustavus; these he rallied, and with them dashed upon the troops of Stalhaus who were pursuing them, and forced them backward. The relief afforded to the Imperialists by this opportune arrival was immense, and leaving Pappenheim to deal with the Swedish right, Wallenstein rallied his own right on the centre, and opposed a fresh front to the advancing troops of Duke Bernhard and Kniphausen. Inspirited by the arrival of the reinforcements, and burning to turn what had just appeared a defeat into a victory, the Imperialists advanced with such ardour that the Swedes were driven back, the guns on the hills recaptured, and it seemed that in this terrible battle victory was at last to declare itself in favour of the Imperialists.
It needed only the return of Pappenheim from the pursuit of the Swedish right to decide the day, but Pappenheim was not to come. Though driven back by the first impetuous charge of the Imperial cavalry, the Swedes under Stalhaus, reinforced by the Scottish regiments under Henderson, stubbornly opposed their further attacks.
While leading his men forward Pappenheim fell with two musketballs through his body. While lying there the rumour for the first time reached him that Gustavus had been killed. When upon inquiry the truth of the rumour was confirmed, the eyes of the dying man lighted up.
“Tell Wallenstein,” he said to the officer nearest to him, “that I am lying here without hope of life, but I die gladly, knowing, as I now know, that the irreconcilable enemy of my faith has fallen on the same day.”
The Imperialists, discouraged by the fall of their general, could not withstand the ardour with which the Swedes and Scottish infantry attacked them, and the cavalry rode from the field. Elsewhere the battle was still raging. Wallenstein's right and centre had driven Count Bernhard, the Duke of Brahe, and Kniphausen across that desperately contested road, but beyond this they could not force them, so stubbornly and desperately did they fight. But Stalhaus and his men, refreshed and invigorated by their victory over Pappenheim's force, again came up and took their part in the fight. Wallenstein had no longer a hope of victory, he fought now only to avoid defeat. The sun had already set, and if he could but maintain his position for another half hour darkness would save his army.
He fell back across the road again, fighting stubbornly and in good order, and extending his line to the left to prevent Stalhaus from turning his flank; and in this order the terrible struggle continued till nightfall. Both sides fought with splendid bravery. The Swedes, eager for the victory once again apparently within their grasp, pressed on with fury, while the Imperialists opposed them with the most stubborn obstinacy.
Seven times did Piccolomini charge with his cavalry upon the advancing Swedes. Seven times was his horse shot under him, but remounting each time, he drew off his men in good order, and in readiness to dash forward again at the first opportunity. The other Imperialist generals fought with equal courage and coolness, while Wallenstein, present wherever the danger was thickest, animated all by his courage and coolness. Though forced step by step to retire, the Imperialists never lost their formation, never turned their backs to the foe; and thus the fight went on till the darkness gathered thicker and thicker, the combatants could no longer see each other, and the desperate battle came to an end.
In the darkness, Wallenstein drew off his army and fell back to Leipzig, leaving behind him his colours and all his guns. In thus doing he threw away the opportunity of turning what his retreat acknowledged to be a defeat into a victory on the following morning, for scarcely had he left the field when the six regiments of Pappenheim's infantry arrived from Halle. Had he held his ground he could have renewed the battle in the morning, with the best prospects of success, for the struggle of the preceding day had been little more than a drawn battle, and the accessions of fresh troops should have given him a decided advantage over the weary Swedes. The newcomers, finding the field deserted, and learning from the wounded lying thickly over it that Wallenstein had retreated, at once marched away.
In the Swedish camp there was no assurance whatever that a victory had been gained, for nightfall had fallen on the Imperialists fighting as stubbornly as ever. The loss of the king, the master spirit of the war, dispirited and discouraged them, and Duke Bernhard and Kniphausen held in the darkness an anxious consultation as to whether the army should not at once retreat to Weissenburg. The plan was not carried out, only because it was considered that it was impracticable—as the army would be exposed to destruction should the Imperialists fall upon them while crossing the terrible morass in their rear.