Complex sentence: In 1860 when the American Civil War broke out Indiana would remain part of the Union and contribute over 200,000 men to suppress the rebellion and by that act also end slavery in the United States for ever.
Split into simpler sentences: In 1860 when the American Civil War broke out Indiana would remain part of the Union and contribute over 200,000 men to suppress the rebellion. By that act Hoosiers helped end slavery in the United States for ever.