The foremost characteristic of a regular army is the soldiers who form the basic unit. We can define a good army by:
The Regular Army: It comprises of the troops who volunteers to fight for the state. They are recruited from the different state. The modern day Indian army has soldiers from Punjab, Himachal Pradesh, Tamil Nadu and all other states.
Mercenary Force: A mercenary force is a temporary recruitment done for a specific purpose. Once the task is carried out the mercenary force is disbanded. The soldiers fight only for the money and therefore less motivated. As compared to Regular Army they are not well trained, motivated and disciplined.
How well a soldier is trained? Soldiers who are well trained always perform well. It gives them added confidence in doing their task. A well-trained regular army enjoyed the confidence of the King because of their loyalty, their skills with weapons and their motivation.
How well an army is organized and how well it is disciplined:
In the Varna system followed by ancient Indians, a Kshatriya was considered as the best warrior. There was however no restriction on hiring soldiers from any of the other castes. According to Kautilya, a body of troops who are of the same region and caste become a great asset. Sukraniti describes the characteristics of a good army.
Thiruvalluvar, the author of Thirukkural, says that homogeneity, tradition and valour were the most important characteristics of a good army. The Tanjore inscriptions are testimonial to the recording of 31 regiments of regular units in the Chola army. It is interesting to note that some regiments were assigned duties such as guarding the temple or being temple musicians. Even today the army has units which perform other national building tools tasks like afforestation, building roads & bridges, etc.
Armies are organized as per the weapons they carry and their role in the battle. In the ancient age, one chariot, one elephant, three horses and three infantry soldiers formed the basic unit and was called Patti. This was the smallest unit of the army. Such a unit was complimentary to each other. For example, the three infantry soldiers protected the elephants and the three horses could scout ahead as sentries to look out for enemy.
This smallest unit was then grouped with similar units to form larger forces. The largest such unit formation was called Aksauhini and was considered to represent the complete army. Large armies had hundreds of chariots, elephants and foot soldiers. A well organized army became a cohesive fighting unit and thus constituted a good army.