Complex sentence: In 983, as part of the Great Slav Rising, the Lutici initiated an open rebellion, and in the ensuing war (983-995) succeeded in reclaiming their independence and the lose of the Billung March and Northern March by the Empire.
Split into simpler sentences: In 983, as part of the Great Slav Rising, the Lutici initiated an open rebellion. In the ensuing war (983-995), the Lutici succeeded in reclaiming their independence and gained control of the Billung March and Northern March from the Empire.