Signal Corps.—1 colonel, 1 lieutenant-colonel, 2 majors.
Quartermaster's Department.—1 brigadier-general, 3 colonels, 4 lieutenant-colonels, 11 majors, 48 captains, 12 military storekeepers.
Subsistence Department.—1 brigadier-general, 2 colonels, 2 lieutenant-colonels, 8 majors, 16 captains.
Medical Department.—1 brigadier-general, 2 colonels, 16 lieutenant-colonels, 50 majors, 5 captains, 109 first lieutenants, 6 storekeepers, 119 hospital chaplains, 70 medical cadets.
Pay Department.—1 colonel, 2 lieutenant-colonels, 25 majors.
Corps of Engineers.—1 brigadier-general, 4 colonels, 10 lieutenant-colonels, 20 majors, 30 captains, 30 first lieutenants, 10 second lieutenants. The battalion of engineers comprises a total of 805.
Ordnance Department.—1 brigadier-general, 2 colonels, 3 lieutenant-colonels, 6 majors, 20 captains, 20 first lieutenants, 12 second lieutenants, 15 storekeepers, and a battalion of 905 men.
These figures all pertain to the regular army. A considerable number of the officers in the regiments have been appointed from civil life; but in the staff departments the officers are almost exclusively graduates from the Military Academy at West Point.
The raising of the immense volunteer force necessitated a great increase in the staff departments, and large numbers of persons from civil life have been appointed into the volunteer staff in the Adjutant-General's, Judge-Advocate's, Quartermaster's, Commissary, Medical, and Pay Departments. The ordnance duties are performed by officers detailed from the line, and engineer duties by regiments assigned for that purpose. A large number of additional aides-de-camp were also authorized, forming that branch of duty into a department. Aides-de-camp are also detailed from the line. The highest rank yet created for volunteer staff officers is that of colonel in the aides-de-camp. The heads of staff departments at corps headquarters are lieutenant-colonels, including an assistant adjutant-general, assistant inspector-general, a chief quartermaster, and chief commissary. Many regular officers hold these volunteer staff appointments, gaining in this manner additional rank during the war—still retaining their positions in the regular service; in the same manner as many regular officers are field officers in volunteer regiments.
The aggregate militia force of the United States (including seceded portions), according to the last returns, was 3,214,769. The reports of the last census increase this to about 5,600,000, which exceeds to some extent the number actually fit to bear arms. The computed proportion in Europe of the number of men who can be called into the field is about one-fifth or one-sixth of the population. If the population of the entire United States be assumed to be 23,000,000, the number of men liable, according to this computation, would be about 4,000,000, which is sufficiently approximate. The European computation of the force to be kept as a standing army is a hundredth part of the population—varied somewhat by circumstances. This would give the United States a force of 230,000. It will be seen how greatly inferior our regular force has been and still is to the computations adopted in Europe. But the United States will probably never require such a large force to be permanently organized; for we have not, like the European powers, frontiers to protect against nations with whom we may at any time be at war, nor oppressed nationalities to retain in subjugation by force. Our frontiers on Canada and Mexico have good natural defences—the first by the St. Lawrence river and lakes, and the second by the great distance to be traversed by an invading army before it could reach any important commercial position. Our vulnerability is in our extensive seacoast. The principal requirement for an army is a large framework, which can be rapidly filled by volunteers in expectation of war. With such a military constitution and a system of military education and drill in the different States, large and effective armies could be rapidly organized.