The Imperial invasion of Earth, also known as the First Earth-Empire war, was a conflict between the United Nations, the Galactic Empire, and the Islamic Fundamentalist groups, who saw an opportunity to establish a new world-wide Caliphate.
The U.N victories at the Second Battle of Cartagena and the Third Battle of Jerusalem in 16 BBY convinced the Empire that the goals of the invasion were impossible to accomplish, leading to a complete withdrawal of the Imperial Army in 16 BBY, leaving several ships and weapons behind, which were used by the Earthlings to create an authentic space miliatry, and later inserted another war.