Complex sentence: In their action at Ètreux, only four officers and 240 other ranks of the 2nd Munsters survived but the Battalion prevented German pursuit of the BEF I Corps gaining valuable time for the BEF to escape.
Split into simpler sentences: In their action at Ètreux the 2nd Munsters were decimated, with only four officers and 240 other ranks surviving. Nevertheless, the Battalion's action effectively prevented German pursuit of the BEF I Corps gaining valuable time for the BEF to escape.