FORCE STRUCTURE
Prior to the military reforms of Tiglath-Pileser III (745 - 727 BC), in common with other armies of the Ancient Near East, the ability of Assyrian forces to mount military campaigns was largely dictated by the agricultural cycle. Reflecting the fact that the economy of Assyria was grounded in agriculture, and the peasants who formed the bulk of the army were needed to service its land and reap the harvest, not until the harvest was collected in May could the peasantry be levied for military service. In practice, this meant Assyrian forces would be ready for campaigning by July. In addition to the Assyrian peasantry, the levy included groups of hillman and semi-nomads who dwelt within the boundaries of the empire. A permanent cadre of the civil service was responsible for carrying out the census which allowed the population to be mobilized for military and policing operations as well as for major construction projects, canal clearing, etc.
Available for compaigning in addition to the levy were the chariotry of nobility and the king's small standing army comprised of the royal bodyguard, Kisir sarruti , with its contingent of foreigners.
As the bulk of Assyrian forces were comprised of peasant farmers, military operations could not be extended beyond the agricultural timetable without causing major economic dislocation. 0 As mobilizations became increasingly frequent, the need for specialist skills more apparent, and the demands on Assyrian manpower ever greater, it became necessary to restructure the military organization of the Assyrian state.
The reform of the Assyrian army was undertaken by Tiglath-Pileser III, previously governor of Kalhu, who in a bloody coup eliminated the royal family and assumed the throne in 745 BC. To free Assyrian forces from the constraints imposed by the agricultural cycle, he reorganized the army, transforming it from a seasonal, conscripted native levy to a standing army available for service throughout the empire. The bulk of the manpower for the new standing army was provided by contingents raised from the provinces within the empire. As was Assyrian custom since the second millenium BC, foreign mercenaries and captives were drafted for service in the Assyrian army as well. Additionally, units provided by vassals, whose service was required as part of the tribute levels of the King, were available for service with Assyrian forces. Foreign troops incorporated into the Kisir sarruti, or standing army, were issued Assyrian uniforms and equipment, rendering them indistinguishable from native professional Assyrian units. The latter served principally in the cavalry and chariot arm of the Kisir sarruti.
Alongside the permanent standing army served the qurubti sha shepe, or the royal bodyguard, composed of cavalry, chariotry and infantry. On campaigns, the sa shepe and Kisir sarruti could be reinforced by the sha sharri , levies raised by the provincial governors (see Command Structure) on the orders of the king. These forces were armed and equipped according to local custom. With the creation of the Kisir sarruti , Assyrian forces now possessed the capability to conduct military operations year-round without disrupting the agricultural cycle or the economy.
As Assyrian forces became more specialized and increasingly greater stress was placed on offense, action units of cavalry and chariots were raised and classified as "well-equipped" or lightly-armed" according to the weapons and defensive armaments they carried. These units were called Pethallu to distinguish them from nonmilitary mounted messengers, Kallapu.
Some non-Assyrian populations living within the boundaries of the empire, such as the Itu and Gurra living near Babylon and the eastern hills were permanently assigned the role of police and semimilitary frontier guards somewhat analogous to the role the Gurkhas played in the British army.