Under whose reign did the Persian empire become the greatest military power of the ancient world?

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Read widely -- and then decide which emperor created "the greatest military power."

To determine under whose reign the Persian Empire became the greatest military power of the ancient world, we need to understand the historical context and consider the rulers who were instrumental in shaping the empire's military might. The Persian Empire, also known as the Achaemenid Empire, spanned from 550 to 330 BCE and had several significant rulers. One name that stands out is King Cyrus the Great.

Cyrus the Great, who reigned from 550 to 530 BCE, laid the foundation for the Persian Empire's military strength. He initiated a series of military campaigns that expanded the empire's territories and established a vast empire encompassing modern-day Iran, Iraq, Syria, and parts of Egypt, Anatolia (Turkey), and Central Asia. Cyrus was known for his strategic acumen and his ability to incorporate conquered peoples into the Persian Empire, which ensured stability and allowed for further military advancements.

However, it was under the reign of Cyrus' successors, particularly King Darius I (r. 522-486 BCE), that the Persian Empire became the greatest military power of the ancient world. King Darius I implemented military reforms that significantly boosted the empire's military capabilities. He divided the empire into administrative regions called satrapies, each led by a satrap who maintained both civil and military control over their region. This decentralized system allowed for more efficient governance and military coordination.

Furthermore, Darius organized a professional standing army known as the Immortals, composed of 10,000 elite soldiers who were always maintained at full strength. This highly trained and disciplined force played a crucial role in the Persian Empire's military successes.

Darius I also launched various military campaigns, expanding the empire's borders and consolidating power. Notably, he invaded Greece in the famous Persian Wars, although ultimately unsuccessful, his military campaigns against the Greeks showcased the empire's enormous military power, organization, and resources.

In conclusion, while Cyrus the Great laid the foundation for the Persian Empire's military strength, it was under the reign of King Darius I that the empire became the greatest military power of the ancient world through his military reforms, strategic expansions, and the establishment of a well-organized professional army.