An "army" is divided into two or more corps commanded by a Major-General. A "corps" is "the largest tactical unit of a large army. A corps is usually organized with separate staff, infantry, cavalry, and artillery regiments, as well as auxiliary services, so that it is really a small army complete in itself. A corps is usually composed of three divisions, each commanded by a Major-General or a Brigadier-General. A "corps" is also any body or department of an army which is not detached, but has its own organization and head, as the "Corps of Engineers." Each "division" is composed of three brigades, and there may be an independent brigade of cavalry or artillery called the divisional cavalry or artillery.

A "brigade" consists of three regiments, though there may be more, and it is commanded by a Brigadier-General, and sometimes by a Colonel. A "regiment," which is the administrative unit, is commanded by a Colonel, and it is divided into twelve companies, each composed, under the present law, of a maximum of 150 men for the infantry, 100 men for the cavalry, a total of 18,920 for the artillery corps, and 150 men for the engineers. A "company" is commanded by a Captain. Two or more companies form a "battalion," and the battalion is commanded by a Major.

The relative rank between the officers of the army and navy is as follows : General with Admiral: Lieu-tenant-General with Vice-Admiral; Major-General with Rear-Admiral; Brigadier-General with Commodore; Colonel with Captain; Lieutenant-Colonel with Commander; Major with Lieutenant-Commander; Captain with Lieutenant; First Lieutenant with Lieutenant (junior grade); Second Lieutenant with Ensign.

The pay of the officers in active service is as follows: Lieutenant-General, $11,000; Major-General, $7,500; Brigadier-General, $5,500; Colonel, $3,500; Lieutenant-Colonel, $3,000; Major. $2,500; Mounted Captain, $2,000; Captain on foot, $1,800; regimental Adjutant, $1,800; regimental Quartermaster, $1,800; First Lieutenant, mounted, $1,600; First Lieutenant on foot, $1,500; Second Lieutenant, mounted, $1,500; Second Lieutenant on foot, $1,400. All of the officers from the Colonel down receive additional amounts after five, ten, fifteen and twenty years' service, but there is a limit to this amount; thus the maximum pay of a Colonel is $4,500 per annum. The pay of a private, whether artillery, cavalry or infantry, is $13 per month for the first and second years, $14 for the third year, $15 for the fourth year, $16 for the fifth year. After five years' continuous service they receive $2 per month extra. For service in the insular possessions 20 per cent, is added to the pay of officers and enlisted men.

The present strength of the regular army is about 3,800 officers and 60,000 enlisted men; 13,000 of them are in the Philippines. This does not include 4,800 scouts, who are paid from the Philippine treasury proper.

The policy of the United States in having a small military establishment has led to the organization of a large body of reserves, which are known as the organized militia or "National Guard." According to the latest accounts received at the office of the Adjutant-General in 1903 there were in the National Guard of the various States and Territories 9,184 commissioned officers and 107,422 non-commissioned officers, privates, musicians, etc., making a total of 116,606.

Under the Act of Congress approved January 31, 1903, the militia consists of every able-bodied male citizen of the United States who is more than eighteen and less than forty-five years of age, and is divided into two classes - the organized militia or National Guard, and the remainder to be known as the reserve militia. It is entirely optional whether eligible citizens join the National Guard or not, and they elect their own officers, but it is safe to say that this body of reserves is recruited from the best and most patriotic element of the population of the United States. Congress makes an appropriation each year for the support of the militia in the various States, and the States also contribute, help and build armories, as the regiments are really intended to defend their own States primarily, although in time of war they furnish an excellently drilled body of volunteers. In nearly every city of any great size there is one or more armories, and in the smaller cities and towns there are separate companies which have armories or drill halls. The militia in each State is divided into brigades, regiments and companies. Under the act of Congress above named the President of the United States has the power to call upon any of the military organizations of the States for national defense, but the troops are usually utilized by the Governor of the State for enforcing the State laws.

The experience of the Spanish-American war demonstrated the need of what is known in foreign armies as a General Staff Corps. Accordingly, under the Act of Congress approved February 14, 1903, a Chief of Staff was authorized, to take the place of the commanding general of the army, and a General Staff Corps whose duties are defined as follows: To prepare plans for the national defense and for the mobilization of the military forces in time of war; to investigate and report upon all questions affecting the efficiency of the army and its state of preparation for military operations; to render professional aid and assistance to the Secretary of War and to general officers and other superior commanders, and to act as their agents in informing and co-ordinating the action of the different officers who, under the terms of the act, are subject to the supervision of the Chief of Staff; and to perform such other military duties not otherwise assigned by law, as may from time to time be prescribed by the President.

Under this act a number of officers were detailed in the General Staff for a period of four years, and the corps was organized into three divisions, each under a superior officer, with the following duties: The first division has charge of army administration, discipline, drill and equipment; the second division is the division of military information, and in addition has charge of military maps, military attaches and the War Department library : the third division is termed the technical division, and includes the devising of plans for defense and offense, the matter of sites for fortifications, the question of military education, and the Army War College.

This article has been revised by Captain C. D. Rhodes, U. S. A., of the General Staff Corps, under the direction of Major W. D. Beach, U. S. A., Chief of Staff, Second Division.