As early as 1882 Army leaders realized that heavy fixed artillery required different training programs and tactics than mobile field artillery. The Artillery Corps was divided into two types: field artillery and coast artillery. This process began in February 1901 with the authorization of 30 numbered companies of field artillery (commonly called batteries) and 126 numbered companies of coast artillery. 82 existing heavy batteries were designated coast artillery companies, and 44 new CA companies were created by splitting existing units and filling their ranks with recruits. The head of the Artillery Corps became the Chief of Artillery in the rank of brigadier general with jurisdiction over both types of artillery.
The coast artillery became responsible for the installation and operation of the controlled mine fields that were planted to be under observation, fired electrically and protected by fixed guns.
The U.S. Army Coast Artillery Corps (CAC) was a corps level organization responsible for coastal and harbor defense of the United States between 1901 and 1950.
Coast Artillery Companies 1901-1924
The following listing of serially numbered companies of coast artillery gives their locations and changes in designations from their creation in 1901 until 1924, when the separate company numbers were finally abolished. This list is best used in conjunction with “Coast Artillery Organization: A Brief Overview,” in the May 2008 Coast Defense Journal (Vol. 22 No. 2). Redesignations were effective in the year shown. The year shown for locations indicates that the company was at the new post in that year, but could have arrived there during the previous year. Units in parentheses in the headings indicate the units from which the companies were formed, either by redesignation of lettered companies of the seven artillery regiments in 1901, or by splitting existing companies of coast artillery
43rd Company (I/4th Artillery)
1901 – Fort Trumbull, CT
1901 – Fort Terry, NY
1916 – 1st Company, Fort Terry, NY
1917 – 12th Company, CD Long Island Sound
1918 – 8th Company, CD Long Island Sound
1922 – 43rd Company, CAC
1924 – I/4th CA Regiment (HD), Fort Amador, Panama Canal Zone (CZ)