Complex sentence: This rear-guard action allowed the main column to deploy and setup a defensive perimeter under Lt Colonel Wools-Sampson, that prevented the attacking Boer forces from riding on and capturing it as originally planned.
Split into simpler sentences: This rear-guard action allowed the main column time to deploy and set up a defensive perimeter under Lt Colonel Wools-Sampson. This deployment prevented the attacking Boer forces from riding on and capturing the main column as originally planned.