Endicott Period (1890-1910)
In 1885 US President Grover Cleveland appointed a joint army, navy and civilian board, headed by Secretary of War William C. Endicott, known as the Board of Fortifications. The findings of the board illustrated a grim picture of existing defenses in its 1886 report and recommended a massive $127 million construction program of breechloading cannons, mortars, floating batteries, and submarine mines for some 29 locations on the US coastline.
Prior efforts at harbor defense construction had ceased in 1876. Since that time the design and construction of heavy ordnance advanced rapidly, including the development of superior breechloading and longer-ranged cannon, making the US harbor defenses obsolete. In 1883, the navy had begun a new construction program with an emphasis on offensive rather than defensive warships. These factors combined to create a need for improved coastal defense systems.
The Endicott Board's recommendations would lead to a large scale modernization program of harbor and coastal defenses in the United States, especially the construction of modern reinforced concrete fortifications and the installation of large caliber breechloading artillery and mortar batteries. Typically, Endicott period projects were not fortresses, but a system of well-dispersed emplacements with few but large guns in each location. The structures were usually open-topped concrete walls protected by sloped earthworks. Many of these featured disappearing guns, which sat protected behind the walls, but could be raised to fire. Mine fields were a critical component of the defense, and smaller guns were also employed to protect the mine fields from mine sweeping vessels.