Complex sentence: The monument was built in 1884 by the citizens of Lewis County, which was a Union stronghold during the war and one of the few places in Kentucky that was still more sympathetic to the Union cause by the 1880s.
Split into simpler sentences: The monument was built in 1884 by the citizens of Lewis County. It was a Union stronghold during the war, and was one of the few places in Kentucky that was still more sympathetic to the Union cause by the 1880s.