The Assyrian Empire became a strong military power primarily through the use of cavalry and chariot forces and the use of archers. Both of these military innovations played a significant role in their ability to conquer and control vast territories.
While the Assyrians did utilize bronze weapons, the specific development of bronze itself was not unique to them and was common among many ancient civilizations. The creation of a large, powerful navy was also not a primary factor in their military power, as their major campaigns were conducted on land.
So, the best responses are:
- use of cavalry and chariot forces
- use of archers