Army under Mauryan Empire had a highly complex structure. The Mauryan Empire maintained a large standing army that was adequate to all its internal and external needs. The Arthashastra mentions two different types of chariots -war chariots and chariots used for assaulting fortresses among them. There were superintendents or adhyakshas who were set over each of the four sections. They were charged with the duty of procuring necessary supplies and keeping the men, animals and machines properly. Stress is laid on the elephant corps and great attention is paid to proper maintenance of elephant forces or nagavana.

Kautilya differentiates different types of infantry: hereditary troops, hired troops; troops maintained by guilds and available to the state and forest tribes who furnished troops to the king during war. The organization of the army was an elaborate affair. Different formations based on clear distinctions between vanguard, centre, rear, wings, reserves, and between the requirements of March, attack and defence have also been described in detail. The value and use of different weapons was also canvassed. There were varieties of stationary and mobile engines.

The superintendents of the forces functioning either alone or with the help of boards must have been subject to the general control of the commander-in-chief who was one of the most important officers of the state. Periodical inspections took place which was done by the commander-in-chief. The army was broken into many units and the smallest unit was called a patti. It had one chariot, one elephant, three cavalry and five infantry. The elephant and chariot would be in the centre with the cavalry and infantry surrounding them. Three patti made up a Sena mukha and three Sena Mukha constitute a Gulma. Gana, Vahini, Pratana, Camu and Ani kini were the other divisions, each of which was three times as big as the one preceding it. The Aksauhini consisted of ten Ani kini and was the largest unit in an army.

Formation of Mauryan Army
Mauryan army had multiple Aksauhini`s. Standing army had three-quarter million troops. Mauryan army used a variety of formations. Vyuha formation had a center, two flanks and two wings. Thirty main vyuhas were used which can be divided into four main categories. Padma vyuha or lotus formation is a type of Vyuha.

In `padma vyuha` the Deputy Commanders-in-Chief would be placed at each outer point of the petals and at the inner end, where each end of lotus petal joins with the other, to form an inner-circle resembling the corolla of the lotus, the Commanders-in-Chief would be stationed. In order to reach the centre of the `lotus` the space between two `petals` is the only access. For this purpose if a contingent of enemy soldiers moved between any two petals, the petals would close in and crush the invader.

The Garuda Vyuha or Eagle formation was another formation that was used commonly. It had a `beak` where the best Kshatriya soldiers would be placed in tight wedge formation. The `head,` behind the beak had a small contingent of reserves. War elephants would be placed in the beak and head. Two broad `wings` would sweep out behind the head - the chariots and cavalry placed at the outside. The body consist of reserves behind the wings and the body.

Some other formations include:
Suchi vyuha - Needle formation
Chayana vyuha - Hawk formation
Mala vyuha - Garland formation
Karuncha vyuha - Heron formation
Makara vyuha - Fish formation
Padma vyuha - Lotus formation
Kurma vyuha - Turtle formation
Trishula vyuha - Trident formation
Chakra vyuha - Wheel or Discus formation

The Mauryan army was consisted of people all over the subcontinent. Chandragupta Maurya did not discriminate against different castes which resulted in soldiers from all castes making it diverse.

Uttarapathian warriors made the core of the army. Other people in the Mauryan army include the Maghadas, Assamese and Cheras. Even the Nagas were incorporated into the army.