Complex sentence: The 1st Infantry Division of Army Group South and 32nd Infantry Division of Army Group North were selected to be issued the rifle, both being refitted from heavy losses on the Eastern Front; ammunition shortages meant the 1st ID was the only division fully equipped with it.
Split into simpler sentences: The 1st Infantry Division of Army Group South and 32nd Infantry Division of Army Group North were selected to be issued the rifle, both being refitted from heavy losses on the Eastern Front. Ammunition shortages meant the 1st ID was the only division fully equipped with it.