On November 1, 1915, Parris Island was officially designated a United States Marine Corps Recruit Depot. From the article:
" 6 - Birth of the Depot
There are a number of people who can be considered the “father” of Marine Corps Recruit Depot Parris Island. Some give credit to Commandant George F. Elliott who attempted to establish an Officer’s School of Application and a preliminary school for recruits at New London, Conn. The Navy balked at establishing the New London Depot, but Elliott did gain permission to place the school for officers at the old naval station on Parris Island. The school on Parris Island was officially opened in 1909 during Elliott’s last year as commandant.
Since Elliott had been unable to create a recruit depot, another claimant for the founder of the recruit training facility on Parris Island is Maj. Gen. William P. Biddle, the Corps’ eleventh commandant. Biddle, a strong advocate of training, set recruit training at three months and established small depots at Philadelphia, Parris Island, Mare Island and Puget Sound. However, the depot at Parris Island, which was started in 1911, lasted only one year before the Navy commandeered the buildings for a disciplinary barracks, forcing the Marines to move both their recruit depot and officers school to the Norfolk Navy Yard.
Besides Elliott and Biddle, there is a third commandant who is sometimes touted as the father of recruit training at Parris Island - Maj. Gen. George Barnett, who succeeded Biddle in February 1914. It was under Barnett’s tenure that, in October 1915, the Marines moved the recruit depot from Norfolk back to Parris Island. Though Barnett may have the best claim of all the commandants, the depot would not have been established without help from three politicians from South Carolina, North Carolina and New York, who may be the ones truly responsible for the placement of a permanent depot on Parris Island.
In 1912, a new congressman was elected to South Carolina’s 2nd Congressional District, which at that time included Beaufort County. His name was James F. Byrnes. Known as “Jimmy” Burns, the election launched the career of one of South Carolina's and the nation’s most remarkable politicians and statesmen. His election in 1912 found him working closely with the newly elected Woodrow Wilson administration. Part of Wilson’s political strategy centered on working with southern populist leaders such as Jimmy Byrnes and Josephus Daniels, an influential North Carolina newspaperman. Wilson named Daniels as his Secretary of the Navy, and in September 1913, Daniels visited the disciplinary barracks at Parris Island, which at that time was home to 11 Marine Corps officers, 157 enlisted Marines and 26 sailors who watched over 471 prisoners. During his visit, Daniels promised local leaders that he would pay personal attention to Parris Island.
Three months later, Jimmy Byrnes brought Daniels’ assistant secretary of the Navy, Franklin Delano Roosevelt, to Parris Island. With both Daniels’ and Roosevelt’s backing, Byrnes was able to gain congressional approval to move the recruit depot back to Parris Island from the Norfolk Navy Yard. On April 5, 1915, Daniels informed Byrnes that a Marine Corps post would be established on Parris Island and on Oct. 1, 1915, Byrnes announced to his constituents in Beaufort County that 800 Marines would soon be arriving at the old Navy yard on Parris Island.
On Oct. 25, 1915, the "Marine Barracks, Port Royal, South Carolina" was established. On Oct. 27, 1915, the transport Prairie sailed into Port Royal Sound and disembarked 750 Marines at their new home. The next day, a transfer of property from the Navy to the Marine Corps occurred, and finally, the administration of the Naval Disciplinary Barracks was transferred to the Headquarters Detachment of the newly designated "Marine Barracks" on Nov. 1. Because of the work of numerous individuals - especially the work of Jimmy Byrnes in Congress, along with support from Daniels and Roosevelt - Marines permanently returned to Parris Island, and the depot became the first military facility ever assigned to the exclusive use of the Marine Corps."