As part of a new plan for the defense of Pensacola Bay, work was initiated to modernize the old Spanish water battery. Beginning in 1839, construction crews added a rear wall to the battery, mounted cannon en barbette on its ramparts and built an infantry gallery
on top of the bombproof from which soldiers could use musket fire on any attacking force. On the site of the earlier log and earth forts,
the Americans built Fort Barrancas, a strong masonry fortification. Combined with the reconditioned Water Battery, it functioned with
Fort Pickens on Santa Rosa Island and Fort McRee on Foster's Bank to sweep the bay with fire from hundreds of cannon.