the island to Simeon Leland, a prominent hotelier, who then subleased it to the U.S. War Department for hospital purposes. De Camp General Hospital was soon established, and wooden structures were erected to house thousands of wounded prisoners from the battlefields of the Civil War. By late 1862, De Camp was the Army's largest general hospital, housing more than 2,100 patients. Originally, the hospital treated only Union soldiers, but following the Battle of Gettysburg in July 1863, the War Department opened it to care for hundreds of wounded Confederate soldiers. Davids Island soon held more than 2,500 Confederate prisoners. Most had recovered by October and were moved to prisoner of war camps elsewhere. A ferry connection was established from Neptune Island, under the control of Simeon Leland. At the end of the war, Congress authorized the island's purchase for military purposes, and it was conveyed to the United States in 1867. From this date, the federal government operated its own ferry to and from Neptune Island. In July 1878 Davids Island was made a principal depot of the U.S. Army General Recruiting Service, taking over this assignment from Governors Island. This marked the beginning of the installation's longstanding mission as a recruitment and training center. It was later converted to a coastal artillery defense post and was named Fort Slocum, after Major General Henry W. Slocum, U.S. Volunteers. Between 1891 and 1904, artillery batteries were erected at three places on the eastern half of the island: Battery Practice near the southeastern shoreline; the state-of-the-art heavy mortar battery, Battery Haskin-Overton, near the southern end of the island; and two adjoining medium-range gun batteries, Fraser and Kinney, on the northeastern shore. At the start of the 20th century, the island had become the East Coast assembly point for units being assigned to America's new overseas operations. By the onset of World War I, it had become one of the busiest recruiting stations in the country, processing 100,000 soldiers per year. From 1946 to 1949, Fort Slocum housed the headquarters of the First Air Force. In June 1949, it was renamed "Slocum Air Force Base"; this only lasted for a year before it was turned back into an Army post in June 1950. From 1955 to 1960, Fort Slocum housed Nike Ajax air-defense battery NY-15. The missiles were stored in underground silos on Hart Island with the radar and control base on Davids