Complex sentence: In 69, they provided a "cohort" during the Batavian Revolt, which was destroyed by the Ubii and in 308 joined the alliance against Constantine the Great during his campaign against the Bructeri.
Split into simpler sentences: In 69, they provided a "cohort" during the Batavian Revolt, which was destroyed by the Ubii. In 308 the Tubantes joined the alliance against Constantine the Great during his campaign against the Bructeri.