The Landgrave of Hesse gave Tilly's troops such a severe rebuff that the Imperial army was ordered immediately into Thuringia, but Tilly, hearing where Gustavus and his army were located, made his way to that portion of the country and encamped on the same side of the Elbe River as Gustavus. The Swedes routed three of Tilly's regiments, carried off most of their baggage and burned the remainder. But Gustavus' army had been weakened by much sickness during the winter and he carefully avoided a general engagement, while Tilly considered the entrenchments of the Swedes far too formidable for assault. Tilly wasted considerable time before the Swedish camp, then bent his course toward Saxony. Up to this time this country had been spared, because of the loyalty of its ruling house to Austria, and because Emperor Ferdinand II. earnestly desired to keep Duke John George with his party, but it was a rich country, and now Tilly and his hordes pounced upon it like birds of prey on a carcass. A line of two hundred burning villages marked Tilly's march to the neighborhood of Leipzig. Now the Elector, when the beak of the enemy was at his own vitals, turned quickly to Gustavus. He sent Field Marshal Arnheim to request the immediate help of the king of Sweden. The king must have been gratified, though no word of history shows any exultation on his part. He replied to the Field Marshal: "I am sorry for the Elector; had he heeded my repeated remonstrances his country would never have seen the face of an enemy, and Magdeburg would not have been destroyed. Now, when necessity leaves no other alternative, he seeks my assistance. But tell him that I cannot, for his sake, ruin my own cause and that of my confederates. What pledge have I for the sincerity of a prince whose minister is in the pay of Austria and who will abandon me as soon as the Emperor flatters him and withdraws his troops from Saxony?" In spite of the coldness of the king, Arnheim persisted, for he had been ordered to secure the assistance of the king of Sweden at any price. Arnheim pressed him to name any conditions, saying: "I shall see they are accepted." At last Gustavus said: "I require that the Elector shall cede to me the fortress of Wittenberg, deliver to me his eldest son as hostage, furnish my troops with three months' pay, and deliver up to me the traitors among his ministry." "Not Wittenberg alone," said the Elector, when he had read the message, "but Torgau and all Saxony shall be open to him, my whole family shall be hostages, and if that is not enough, I will place myself in his hands. Return and inform him I am ready to deliver to him any traitors he shall name, to furnish his army with any money he requires, and to venture my life and fortune in the good cause."