Complex sentence: Before federal forces arrived at Charleston in response to challenges on tariffs, Calhoun and Henry Clay agreed upon a Compromise Tariff of 1833 to lower rates over 10 years and the "nullification crisis" was resolved for the time being.
Split into simpler sentences: Before federal forces arrived at Charleston in response to challenges of tariff laws, Calhoun and Henry Clay agreed upon a Compromise Tariff of 1833 to lower the rates over ten years. The "nullification crisis" was resolved for the time being.