Final answer:
Sargon of Akkad, Ramesses II of Egypt, and Cyrus the Great are three leaders known for military campaigns in the region of the Euphrates in Syria. Sargon established the world's first empire and standing army, Ramesses II attempted to reclaim Qadesh from the Hittites, and Cyrus the Great significantly expanded the Persian Empire.
Step-by-step explanation:
The leader who conducted military campaigns as far away as the Euphrates in Syria was Sargon of Akkad. He founded the Akkadian Empire around 2340 BCE, which is noted as the world's first empire. Sargon's empire included regions such as Sumer, Akkad, parts of northern Iraq, Syria, and southwestern Iran. Not only was Sargon known for his extensive conquests, but he also established the world's first standing army.
Another notable leader who conducted operations in the area was Ramesses II of Egypt, who fought the Hittites in Syria in an attempt to reclaim the city of Qadesh. Although he declared victory, the attempt to recapture the city ultimately failed. Nonetheless, his actions further demonstrate the strategic importance of this region throughout history.
Cyrus the Great, founder of the Persian Empire, also expanded his domain to include Mesopotamia, Syria, Phoenicia, and Judah during his conquests in 539 BCE. He is renowned for creating what was, at the time, the largest empire the Near East had ever seen, and for his respectful administration of conquered lands.