Tilly, finding that the position of Gustavus was too strong to be forced, retired to Wolmirstadt, whence he summoned the Elector of Saxony to admit his army into his country, and either to disband the Saxon army or to unite it to his own. Hitherto the elector had held aloof from Gustavus, whom he regarded with jealousy and dislike, and had stood by inactive although the slightest movement of his army would have saved Magdeburg. To disband his troops, however, and to hand over his fortresses to Tilly, would be equivalent to giving up his dominions to the enemy; rather than do this he determined to join Gustavus, and having despatched Arnheim to treat with the King of Sweden for alliance, he sent a point blank refusal to Tilly. The Imperialist general at once marched towards Leipzig, devastating the country as he advanced. Terms were soon arranged between the elector and Gustavus, and on the 3d of September, 1631, the Swedish army crossed the Elbe, and the next day joined the Saxon army at Torgau. By this time Tilly was in front of Leipzig, and immediately on his arrival burned to the ground Halle, a suburb lying beyond the wall, and then summoned the city to surrender. Alarmed at the sight of the conflagration of Halle, and with the fate of Magdeburg in their minds, the citizens of Leipzig opened their gates at once on promise of fair treatment. The news of this speedy surrender was a heavy blow to the allies, who, however, after a council of war, determined at once to march forward against the city, and to give battle to the Imperialists on the plain around it. Leipzig stands on a wide plain which is called the plain of Breitenfeld, and the battle which was about to commence there has been called by the Germans the battle of Breitenfeld, to distinguish it from the even greater struggles which have since taken place under the walls of Leipzig. The baggage had all been left behind, and the Swedish army lay down as they stood. The king occupied his travelling coach, and passed the night chatting with Sir John Hepburn, Marshal Horn, Sir John Banner, Baron Teuffel, who commanded the guards, and other leaders. The lines of red fires which marked Tilly's position on the slope of a gentle eminence to the southwest were plainly to be seen. The day broke dull and misty on the 7th of September, and as the light fog gradually rose the troops formed up for battle. Prayers were said in front of every regiment, and the army then moved forward. Two Scottish brigades had the places of honour in the van, where the regiments of Sir James Ramsay, the Laird of Foulis, and Sir John Hamilton were posted, while Hepburn's Green Brigade formed part of the reserve--a force composed of the best troops of the army, as on them the fate of the battle frequently depends. The Swedish cavalry were commanded by Field Marshal Horn, General Banner, and Lieutenant General Bauditzen.