The Southern sentiments in the area were a growing concern for the Federal Government for sure. We have to keep in mind at one point S. Illinois contemplated joining the Confederacy. I have read that only the intervention of John "Black Jack" Logan prevented this, although Logan harbored Southern sentiments and was at one time himself accused of treason.
Illinois Gov. Rich. Yates himself recieved an anonymous letter from a writer in Southern Illinois stating;
"Some of them say they are going to help Jeff Davis and others say they are going to hang cut throats and shoot every Republican in egypt.. they say it will be sport, killing Republicans as they are scattering"