The diversion which this movement of Mansfeld had made in the plans of Wallenstein, enabled the king to detach a part of his force into Westphalia, to seize the bishoprics of Munster and Osnaburg. To check this movement, Tilly suddenly moved from the Weser; but the operations of Duke Christian, who threatened the territories of the League with an inroad in the direction of Hesse, and to remove thither the seat of war, recalled him as rapidly from Westphalia. In order to keep open his communication with these provinces, and to prevent the junction of the enemy with the Landgrave of Hesse, Tilly hastily seized all the tenable posts on the Werha and Fulda, and took up a strong position in Minden, at the foot of the Hessian Mountains, and at the confluence of these rivers with the Weser. He soon made himself master of Goettingen, the key of Brunswick and Hesse, and was meditating a similar attack upon Nordheim, when the king advanced upon him with his whole army. After throwing into this place the necessary supplies for a long siege, the latter attempted to open a new passage through Eichsfeld and Thuringia, into the territories of the League. He had already reached Duderstadt, when Tilly, by forced marches, came up with him. As the army of Tilly, which had been reinforced by some of Wallenstein's regiments, was superior in numbers to his own, the king, to avoid a battle, retreated towards Brunswick. But Tilly incessantly harassed his retreat, and after three days' skirmishing, he was at length obliged to await the enemy near the village of Lutter in Barenberg. The Danes began the attack with great bravery, and thrice did their intrepid monarch lead them in person against the enemy; but at length the superior numbers and discipline of the Imperialists prevailed, and the general of the League obtained a complete victory. The Danes lost sixty standards, and their whole artillery, baggage, and ammunition. Several officers of distinction and about 4,000 men were killed in the field of battle; and several companies of foot, in the flight, who had thrown themselves into the town-house of Lutter, laid down their arms and surrendered to the conqueror.