Complex sentence: The "Pocosin" was quickly loaded with the wounded and returned from Charleston with 100 armed men of the Palmetto Guard to provide protection for the white citizens of Cainhoy.
Split into simpler sentences: The "Pocosin" was quickly loaded with the wounded. After unloading them at Charleston, it returned with 100 armed men of the Palmetto Guard who intended to provide protection for the white citizens of Cainhoy.