The United States' massive
Endicott and Taft Programs of coast defense construction were no sooner complete than they faced an increasing threat. By 1915 the new forts were almost entirely finished, but the rapid development of
dreadnought battleships threatened to outclass them. One problem was that the
disappearing carriages most of the heavy guns were mounted on limited their elevation to 10 or 15 degrees and hence their range. A new M1917 high-angle
barbette carriage was designed with a maximum elevation of 35 degrees, increasing the range of the existing
12-inch M1895 gun from to . Construction began in 1917 on 14 new two-gun batteries, ten of them on the US East Coast; two one-gun batteries in the
Philippines followed within a few years. Fort Saulsbury included two of these batteries. The
Harbor Defenses of the Delaware were previously Forts
Delaware,
DuPont, and
Mott, all near
Delaware City. They were sited well north in the
Delaware estuary due to the short range of their guns. The long-range guns of Fort Saulsbury allowed an enemy to be engaged much further south. Fort Saulsbury consisted of Batteries Hall and Haslet, each with two 12-inch guns and a large ammunition and
fire control bunker constructed of reinforced concrete and earth. Circa 1940 five
fire control towers were built to support Fort Saulsbury. These were located at
South Bowers Beach, Big Stone Beach,
Cedar Beach,
Fowler's Beach and
Broadkill Beach. Only the Big Stone Beach tower remains as of 2020. In early 1943 Battery Haslet's guns were relocated to Battery 519 at
Fort Miles. ==Present==