Constantine the Great divided the Roman Empire into Eastern and Western halves.

Explanation:

1. Background: The Roman Empire was a vast and powerful empire that existed from 27 BC to 476 AD. At its height, it controlled a significant portion of Europe, North Africa, and the Middle East. However, as the empire grew, it became increasingly difficult to govern such a vast territory.

2. Constantine the Great: Constantine the Great was a Roman emperor who ruled from 306 to 337 AD. He is known for his many accomplishments, including the Edict of Milan, which granted religious tolerance to Christians, and the founding of the city of Constantinople.

3. Division of the Empire: In order to better manage the empire, Constantine made the decision to divide it into Eastern and Western halves. This division took place in 286 AD. The Western Roman Empire was centered in Rome, while the Eastern Roman Empire was centered in Constantinople.

4. Reasons for Division: There were several reasons why Constantine chose to divide the empire:

- Geographic Distance: The vast size of the empire made communication and administration difficult. By dividing it into two halves, Constantine hoped to improve governance and coordination.
- Military Defense: The empire faced numerous external threats, including invasions from barbarian tribes. By establishing separate military commands in the East and West, Constantine aimed to strengthen the empire's defense capabilities.
- Economic Stability: The division allowed for better management of resources and trade routes. The Eastern half, with its capital at Constantinople, was strategically located for trade with Asia and the Middle East.

5. Legacy: The division of the Roman Empire by Constantine had long-lasting consequences. The Western Roman Empire eventually fell in 476 AD, while the Eastern Roman Empire, also known as the Byzantine Empire, continued to thrive for several more centuries.

In conclusion, Constantine the Great is the Roman emperor who divided the Roman Empire into Eastern and Western halves. This division was a significant event in Roman history and had far-reaching implications for the future of the empire.