Complex sentence: The last military troops organized in Indianapolis was the 156th Indiana Infantry Regiment, which mustered into service on April 12,1865; however, most of the city's military camps were closed by the autumn of 1865.
Split into simpler sentences: The last military troops organized in Indianapolis was the 156th Indiana Infantry Regiment, which mustered into service on April 12,1865. Most of the city's military camps were closed by the autumn of 1865.