Gratianus, however, thought that he could not leave Gaul and the Rhine until he had first punished the Alemanni for their recent incursions across the frontier, and--at least for a while--deterred them from making new inroads. At the same time he desired, in case the summons for help should arrive, to have traversed a portion of the long distance and thus be able to give his uncle aid more speedily. So, toward the end of July, he left his residence, Trier, with the larger portion of his troops, and marched by way of Zabern and Strassburg to the left bank of the Rhine near Augst and Basle. Here and at Windisch he formed two camps and kept the main body of his troops near him, busying himself in the reorganization of the province and eagerly awaiting news from the East. The expedition against the Alemanni on the northern shore of the lake was entrusted to a small band of troops which, being able to move more swiftly, seemed better suited for the marches through swamp and forest and, moreover, amply sufficient in number; for the attack was directed against only the Linzgau, so called from the little river, which at the present time is still known as the Linz, or more frequently the Ach. This was the home of the Lentian Alemanni, who lived on the northern and western shores of the lake and, during that very spring, had harried the Roman frontier. The command of the expedition had been entrusted to experienced generals who had chosen their own force of foot and horse, while a large baggage train conveyed the provisions and the remainder of the luggage. In all, there were probably more than three thousand men. According to the old victorious Roman strategy--whose success was proved by the conquest of nearly half the world known at that day--this small force was to assail the foe from several directions at once, the same as in great campaigns, as if seized by claws, a favorite comparison in Roman military literature. Part of the troops--the cavalry, several squadrons of cataphractarii (mailed riders, who were completely sheathed in armor), cohorts of the Twenty-Second Legion, picked German mercenaries, Batavians (they were considered the best of all the foreign soldiers), and lastly the flower of the Imperial Guard, foot-soldiers, mainly Illyrians and Thracians, were to march northward from Windisch, cross the Rhine, move along the old road to the north, then, suddenly turning eastward, skirt the western shore of the lake to gain its northern side, thus penetrating the whole Linzgau from the west to the east, halting at an appointed place in the heart of the enemy's country and awaiting the second division. Meanwhile this second body was to march along the great highway bordering the southern shore from Windisch to Arbon, cross the lake in boats, land on the northern shore, and pass through the Linzgau from east to west till they reached the first division.