Complex sentence: There was another detachment which remained in the South, under the command of Lt Col. Alured Clarke: these men remained in garrison in Charleston, until they were transferred to Savannah, Georgia in December 1781.
Split into simpler sentences: There was another detachment which remained in the South, under the command of Lt Col. Alured Clarke. These men remained in garrison in Charleston, until they were transferred to Savannah, Georgia in December 1781.