In November 1856, ink manufacturer Thaddeus Davids purchased the island, after which time the island took his name. Davids had intended to move his factory to the island but never did so. In 1862, he leased 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.