The Royal Siamese Army was organized into three general tiers: the Palace Guards, the Capital Defense Corps, and the field levies.

The third, the field levies or conscripts, were usually raised just prior to or during wartime, and provided manpower to resist attacks and project power beyond the boundaries of the empire.

Most of the field levy served in the infantry but the men for the elephantry, cavalry, artillery and naval corps were drawn from specific hereditary villages that specialized in respective military skills.

Although the elephantry units made up only about one percent of the overall strength, they were a major component of Siamese war strategy throughout the imperial era.

During the 16th century, the Siamese artillery and musketeer corps were originally made up exclusively of foreign (European and Muslim) mercenaries.