In February the circle determined to levy troops and prepare for war. But the preparations were rather directed against Mansfeld than against Tilly. If the Emperor could only have given satisfaction about the bishoprics, he would have had no vassals more loyal than the Lower Saxon princes. But in Ferdinand's eyes to acknowledge more than had been acknowledged at Mühlhausen would be to make himself partaker in other men's sins. It would have been to acknowledge that robbery might give a lawful title to possession. [Sidenote: § 5. Christian invited to take service under his brother.] Almost unavoidably the circle became further involved in opposition to the Emperor. Christian's brother, Frederick Ulric, the reigning Duke of Brunswick-Wolfenbüttel, was a weak and incompetent prince much under his mother's guidance. Anxious to save her favourite son, the dashing Christian, from destruction, the Duchess persuaded the Duke to offer his brother a refuge in his dominions. If he would bring his troops there, he and they would be taken into the service of the Duke, a respectable law-abiding prince, and time would be afforded him to make his peace with the Emperor. [Sidenote: § 6. The Battle of Stadtlohn.] Christian at once accepted the offer, and entered into negotiations with Ferdinand. But he had never any thought of really abandoning his adventurous career. Young princes, eager for distinction, levied troops and gathered round his standard. Every week the number of his followers increased. At last the neighbouring states could bear it no longer. The authorities of the circle told him plainly to be gone. Reproaching them for their sluggishness in thus abandoning the cause of the Gospel, he started for the Dutch Netherlands, with Tilly following closely upon him. On August 6 he was overtaken at Stadtlohn, within a few hours' march of the frontier, behind which he would have been in safety. His hastily levied recruits were no match for Tilly's veterans. Of 20,000 men only 6,000 found their way across the border. SECTION III.--_Danger of the Lower Saxon Circle._ [Sidenote: § 1. Danger of the Northern bishoprics.]