pation of the whole or any part of the National Guard in encampments, maneuvers, and other training exercises, either independently or in conjunction with Regular Army troops.
c. The organization of all units of the National Guard is the same as that of the Regular Army. The President prescribes the particular unit or units of each branch of the service to be maintained in each state, territory, or the District of Columbia, and assigns these units to divisions, brigades, and other tactical units. The basis of this assignment contemplates an ultimate war establishment of eighteen divisions, four cavalry divisions, and other units. In time of peace these units have a reduced or "maintenance" strength.
d. On the outbreak of war, the National Guard supplements the Regular Army in constituting the first line of defense.
6.Organized Reserves.—a. The Organized Reserves consist of the Officers' Reserve Corps, the Enlisted Reserve Corps, and the Organized Reserve Units. They include troops of all branches necessary to supplement the Regular Army and National Guard in order to complete the first line of defense in a mobilization of the Army of the United States. In time of peace, they are a potential, rather than an actual fighting force. The peace establishment is capable of rapid expansion by the reception of trained and untrained men, but will require a period of training in mobilization areas before becoming available for combat operations.
b. The Officers' Reserve Corps is composed of selected citizens who voluntarily accept commissions in that corps as general officers and as officers of all grades of the line and staff branches of the army. It provides the great mass of officers required for war. In time of a national emergency expressly declared by Congress, the President may order reserve officers to active duty for any period of time. Under other circumstances, he may order them to active duty at any time, but for not more than fifteen days in one calendar year without the consent of the officer concerned.
c. The Enlisted Reserve Corps is composed of persons voluntarily enlisted for service in this corps. Members of
