The following table illustrates what was accomplished by the two recruit depots:
| Depot. | In training— | Maximum strength of post. | Maximum number of recruits at one time. | Total recruits handled. | Maximum capacity. | |
| Apr. 6, 1917. | Nov. 11, 1918. | |||||
| Parris Island | 835 | 4,104 | 16,601 | 13,286 | 46,202 | 13,060 |
| Mare Island | 358 | 1,143 | 2,799 | 2,470 | 11,901 | 3,000 |
| Total | 1,193 | 5,247 | 19,400 | 15,756 | 58,103 | 16,060 |
After leaving the recruit depots at Parris Island and Mare Island, advanced training was given the men at Quantico, Va. This training was most intensive and as a result all the organizations which were trained there attained a high state of efficiency. It was made to approximate as nearly as practicable the real service which the men would have in the American Expeditionary Forces in France. Officers who were engaged in this training showed great ingenuity and efficiency in their attempts to make the training approach as nearly as possible what the men would be subjected to in actual service. That they succeeded was shown by the work done by the Marines in France and other places.
The first troops arrived at the Marine barracks, Quantico, Va., on May 18, 1917. The maximum enlisted strength was 9,849 on September 12, 1918. The maximum number of officers present at one time was 484, on August 16, 1918. The strength on November 11, 1918, was 329 officers and 8,798 enlisted men. From May, 1917, to November 11, 1918, approximately 1,000 officers and 40,000 enlisted men passed through Quantico, Va.
In addition to giving the enlisted men general training at Quantico in preparation for overseas and other duty, the Overseas Depot was established on May 19, 1918, for the double purpose of organizing and training units of the Marine Corps for service with the American Expeditionary Forces.
Prior to the organization of this depot the Fifth and Sixth Regiments, the Sixth Machine Gun Battalion, the Base Battalion of the Fifth Regiment, and two replacement battalions had left the United States and had become part of the American Expeditionary Force.
The Overseas Depot consisted of an administrative staff and the various sections as follows: (a) The specialists’ schools for the technical training of the infantry and machine gun, and the coordination of these specialists’ arms; (b) the tactical department for the instruction and training of overseas units in new tactical principles; (c) the enlisted staff school for the training of first sergeants, mess sergeants, cooks, company clerks, armorers, etc. Two French and four Canadian officers, who had abundant experience in the fighting in Europe, were assigned as advisors of the commanding officer.
The basic independent unit of organization was the platoon, and the platoon therefore became the principal training unit. In the organization of this unit the scheme followed was to assure to each a certain nucleus of enlisted instructors trained in the various specialties, in addition to the platoon commanders, who were qualified to carry on the instruction along approved lines within the unit. This nucleus was taken from the graduates of the specialists’ schools of the depot. When four such platoons had been formed they were assembled into a company. The company headquarters, trained in the enlisted staff school, was added to the four platoons and the company organization was turned over to the company commander complete in all details. Battalions were likewise formed by the consolidation of companies. In every instance the platoon, company, and the battalion, carried out a regular schedule of drills and instructions under the supervision of the depot, but all administrative details were left in the hands of the company and the battalion commanders. These training schedules were made up in the tactical department, approved by the commanding officer, and were based on the most approved methods in effect at the time. In the cases of the formation of regimental organizations, of which there were two formed during the existence of the Overseas Depot, the battalions upon being formed were turned over to the regimental commander, and in this case direct supervision by the depot ceased, but all facilities on hand, such as material, officers acting in an advisory capacity, training areas, etc., directly attached to the depot, were placed at the disposal of the regimental commanders who were at all times in active liaison with the depot.
About 85 per cent of the troops forming the detachments arriving at the Overseas Depot for service in France had undergone not less than 8 nor more than 12 weeks’ training at the regular recruit depots of the Marine Corps. The preliminary training received at these recruit depots was such as to fit the men for general service throughout the Marine Corps, and resulted in the men being well disciplined, considering the short time they had been in the service. This facilitated the more advanced and specialized training they were to receive at the Overseas Depot. These detachments were composed entirely of qualified riflemen, having undergone during the recruit period a most thorough and comprehensive course in the use of the rifle. Upon the arrival of these detachments they were organized as outlined above, and the commissioned personnel was assigned to the units from the officers’ school. The schedule and drills and instructions were provided them and were carried out under the supervision of specially selected officers of the tactical department of the Overseas Depot, including the foreign officers. This training continued until the units departed for France. Training in open warfare was given precedence over that of trench warfare from the very beginning in the proportion of about four to one.