Military Personnel is the size of a state’s military personnel in each year for the period 1816-2016.

Data Acquisition and Generation

Military personnel are defined as troops under the command of the national government, intended for use against foreign adversaries, and held ready for combat as of January 1 of the referent year. It is important to note that any date besides January 1st would have been appropriate for the majority of cases because the data values change slowly. On occasion, however, there are instances where there are rapid changes in troop strength, such as mobilizations for conflicts and wars. Short-term variations in strength are not reflected in the project's data unless the changes remained in effect until the following January 1. With this definition in place, there are five important aspects of quantifying military personnel that need elaboration.

First, the project counted only those troops under the command of the national government. These troop strengths include active, regular military units of the land, naval, and air components. Troops in the reserves such as those found in the United States were not included in the state’s annual total. Colonial troops (such as Indian troops under British command during India’s colonial period) were usually not included in this total if they were a separately administered force.

Second, the military personnel data exclude the military forces of foreign military forces, semi-autonomous states and protectorates, and insurgent troops. Such units were not part of a regular national armed force under a military chain of command. Their inclusion would distort the number of personnel that could be summoned when deemed necessary.

Third, these figures reflect the project's best judgment on which forces were intended for combat with foreign parties. Irregular forces such as civil defense units, frontier guards, gendarmerie, carabineri, and other quasi-military units were nominally responsible for defending outlying districts or for internal security and could be mobilized in time of war. We usually excluded them, however, because they were not integral to the regular armed forces (e.g. Cossack troops of nineteenth century Russia). When these forces were the only military a nation had they were still excluded (e.g. Costa Rica and Switzerland).

A fourth aspect concerns armed forces in several semi-feudal nations, including the warlord armies in pre-modern Japan and China, and Jannissary troops in the Ottoman Empire. Not all nations were quick to adopt Western military organization. We counted only those forces that were acting at the behest of the central government. For example, we included only the Imperial troops and those armies of feudal lords operating on the behalf of the throne in the case of pre-modern Japan.

A final aspect concerns national police forces organized for both foreign and domestic purposes and found in several developing nations in the twentieth century. Such units come directly under the military chain of command and are fully a part of the armed forces at the immediate disposal of a national government. Examples include the old National Guard of Nicaragua and the national police forces of many African states. When such forces provided dual functions of foreign combat and internal security, we included them in its military personnel figures; otherwise, they were excluded.

Usually it was only after 1960 that we found ready-made data (including army, navy, and air force totals) meeting our coding criteria and aggregated into the desired totals. Elsewhere, we assembled the data from bits and pieces. Given a figure that did not fully meet our inclusion/exclusion criteria, we used it only after locating supplementary information that could be used to adjust it. Confronted with conflicting figures, we adopted those that best matched the contemporary data, and only if they seemed historically plausible. In practice, frequently it was impossible to find documentation reflecting the January 1 criterion. In most such cases, however, the figures were changing sufficiently slowly to afford an acceptable approximation. In cases of rapid military change, such as the onset of war, we took note of the fact in arriving at a plausible estimate. Because of the relatively great sensitivity of personnel levels to transitory circumstances such as war involvement, we used estimates to fill missing entries only when they did not occur in such circumstances.