The Battle of Carchemish was fought about 605 BC between the allied armies of Egypt

Late Period of Ancient Egypt

The Late Period of Ancient Egypt refers to the last flowering of native Egyptian rulers after the Third Intermediate Period from the 26th Saite Dynasty into Persian conquests and ended with the death of Alexander the Great...

 and Assyria against Babylonia

Neo-Babylonian Empire

The Neo-Babylonian Empire or Second Babylonian Empire was a period of Mesopotamian history which began in 626 BC and ended in 539 BC. During the preceding three centuries, Babylonia had been ruled by their fellow Akkadian speakers and northern neighbours, Assyria. Throughout that time Babylonia...

.
When the Assyria

Assyria

Assyria was a Semitic Akkadian kingdom, extant as a nation state from the mid–23rd century BC to 608 BC centred on the Upper Tigris river, in northern Mesopotamia , that came to rule regional empires a number of times through history. It was named for its original capital, the ancient city of Assur...

n capital Nineveh

Nineveh

Nineveh was an ancient Assyrian city on the eastern bank of the Tigris River, and capital of the Neo Assyrian Empire. Its ruins are across the river from the modern-day major city of Mosul, in the Ninawa Governorate of Iraq....

 was overrun by the Babylonians in 612 BC, the Assyrians moved their capital to Harran

Harran

Harran was a major ancient city in Upper Mesopotamia whose site is near the modern village of Altınbaşak, Turkey, 24 miles southeast of Şanlıurfa...

. When Harran was captured by the Babylonians in 610 BC, the capital was once again moved, this time to Carchemish, on the Euphrates

Euphrates

The Euphrates is the longest and one of the most historically important rivers of Western Asia. Together with the Tigris, it is one of the two defining rivers of Mesopotamia...

 river.