Complex sentence: While it is believed that they were not particularly numerous, the exact number of Hoosiers to serve in Confederate armies is unknown; it is likely that most of them traveled to Kentucky to join Confederate regiments that formed there.
Split into simpler sentences: While it is believed that they were not particularly numerous, the exact number of Hoosiers to serve in Confederate armies is unknown. It is likely that most of them traveled to Kentucky to join Confederate regiments that formed there.