Ancient history

What was most significant contribution that Gaius Marius made for ancient Rome?

Marius' most significant contribution was his military reform.

He abandoned the traditional Roman practice of relying on a citizen militia and instead created a professional standing army. This army, composed of paid volunteers, was more disciplined, better trained, and more effective than the old citizen militia. Marius military reform allowed Rome to maintain a large, permanent army that could be deployed quickly and effectively to any part of the empire. This proved to be a major advantage in the many wars that Rome fought during this period and helped to ensure the continued expansion of the Roman Empire.