During the Williamite Wars of 1690–1691, the garrison espoused the cause of James II in contrast with that of Birr, which took the side of William. A stone bridge across the Shannon was erected in 1685, and a Williamite army advancing from Birr in 1690 attempted to break it down but abandoned the attempt as too risky in consequence of the presence of Sarsfield's Army on the Connacht side. A broken arch of this bridge is still to be seen on that side a few yards below the present bridge of seven arches, which was erected by the Commissioners for the Improvement of Navigation of the Shannon in 1841–1843. The square tower on the lower side of the bridge at the Galway end was erected to protect the old bridge, as was the Salt Battery, with emplacements for four cannons facing west and north, a few hundred yards from town along the Crank Road.