Because people were afraid of such attacks from other kings and needed protection.

Kings of the Mahajanapadas and their Armies

The kings of the Mahajanapadas, which were ancient kingdoms in India, maintained large armies and fortified their capitals for various reasons. Let's delve into the details:

1. Protection against external threats:
- The Mahajanapadas were often engaged in conflicts and wars with neighboring kingdoms. Maintaining a big army was crucial for defending their territories from invasions.
- The fortified capitals with strong walls, watchtowers, and moats served as a defensive measure to protect the kings, their subjects, and their wealth from external threats.

2. Expansion and conquest:
- The kings of the Mahajanapadas aimed to expand their territories and exert their influence over neighboring regions. A large army was necessary to wage wars and conquer new territories.
- The fortified capitals provided a strategic base from where the kings could launch military campaigns, control their empire, and maintain political dominance.

3. Deterrence and display of power:
- Maintaining a big army and fortifying their capitals helped the kings establish a sense of power and authority. It acted as a deterrent against potential enemies and dissuaded them from attacking.
- The grandeur and strength of the fortified capitals also showcased the wealth and military might of the kings, enhancing their reputation and prestige among their subjects and neighboring kingdoms.

4. Internal stability:
- The Mahajanapadas were not always politically stable, and internal conflicts and rivalries were common. A strong army and fortified capital helped the kings maintain control over their subjects and suppress any rebellions or uprisings.
- The presence of a large army in the capital also acted as a symbol of the king's authority and power, deterring potential challengers to the throne.

5. Economic benefits:
- The kings of the Mahajanapadas collected taxes and tributes from their subjects, which formed a significant part of their revenue. Maintaining a large army allowed them to protect their territories and ensure the collection of taxes, thus ensuring a stable economy.
- The fortified capitals provided secure storage for the king's wealth, resources, and treasures, protecting them from theft or plunder.

In conclusion, the kings of the Mahajanapadas maintained big armies and fortified their capitals for protection against external threats, expansion and conquest, deterrence and display of power, internal stability, and economic benefits. These measures helped them establish their dominance, safeguard their territories, maintain control over their subjects, and ensure the prosperity of their kingdoms.