Jeremiah used the outcome of a battle known to Jehoiakim to warn him and the people of Jerusalem. He said Egypt could not protect them from Babylon. Pharaoh Neco believed it was the right time to become the main power in the ancient Near East, so he moved north in 609 BC. Neco spent several years helping parts of the Assyrian army try to stop the Babylonian army's westward advance. However, he was defeated at Carchemish on the Euphrates River in 605 BC. Soon after, the Babylonian army surrounded Jerusalem and forced Jehoiakim to become a Babylonian vassal.