Complex sentence: Gen. Samuel P. Carter against the eastern end of the Confederate defenses at the Cumberland Gap now held by Col. James Edward Rains after Zollicoffer's defeat and death at Mill Springs.
Split into simpler sentences: Gen. Samuel P. Carter against the eastern end of the Confederate defenses at the Cumberland Gap. These defenses were now held by Col. James Edward Rains after Zollicoffer's defeat and death at Mill Springs.