The Germans also had a card up their sleeve. With control over the dams on the Rur, they could release the water from them and flood the Rur valley and everything else downstream of it as far as the Meuse and into the Netherlands. That would cause large scale destruction and destroy Allied bridges over the Rur, isolating all troops east of the river. The Allies did not fully recognize the strategic importance of the dams for some time, and only days before the end of the offensive they made their first specific moves towards them.