Complex sentence: Ever since he was a boy, Samuel Prescott Hildreth had a desire to see the Ohio Country; he acted on his desire during September and October 1806, traveling by horseback to Marietta, Ohio.
Split into simpler sentences: Ever since he was a boy, Samuel Prescott Hildreth had a desire to see the Ohio Country. He acted on his desire during September and October 1806, traveling by horseback to Marietta, Ohio.