mcclernand was born in breckinridge county, kentucky, near hardinsburg, but his family moved to shawneetown, illinois, when he was quite young. his early life and career were similar to that of another illinois lawyer of the time, abraham lincoln. he was largely self-educated and was admitted to the illinois bar in 1832. in that same year he served as a volunteer private in the blackhawk war (lincoln briefly served as a captain).