Acting on this counsel, the four columns concentrated to the south of the Yermûk, near where it was crossed by the military road from Damascus. The Romans, suiting their tactics to the change, also drew together, and, under command of Theodoric, pitched their camp on the northern bank of the river. The place was singular. The Yermûk, taking its rise in the high lands of the Haurân, and fed by many affluents, is a large and swift stream. In its lower course it runs, far below the level of the plain, in a deep and rugged gorge, through which its waters, rapidly descending to the Ghôr, fall into the Jordan at Gadara, below the Lake of Galilee. The battle-ground was probably 30 or 40 miles above the junction. Here the stream, fetching a compass, formed on the northern bank a great plain,--the plain of WACÛSA, bounded on three sides by a sheer precipice. The remaining side was hemmed in by a ravine which nearly closed the circuit. A narrow neck was left for entrance, across which the military road passing, formed the key of the position. The Romans were tempted by the wide expanse of level ground, which offered room for their great camp, and was secure on every side. Advancing, therefore, from the north, they entered this plain, and spread themselves out upon it. Thereupon the Moslems crossed the river, and encamped also on the northern bank, upon another plain adjoining the neck; thus they commanded the road, and threatened the exit of the enemy. Amru, seeing this, rejoiced and said: ‘Be of good cheer, my friends; the Romans are shut in, and few that are shut in escape.’[158] A desultory warfare ensued without any definite result. The Romans often formed up in force, and as often were driven back; but the ravine was to them a strong protection, and the Arabs gained no material advantage. In such indecisive skirmishing two months passed away, and the armies remained still facing one another.[159] [Sidenote: Khâlid transferred to Syria.]