Complex sentence: Heavier infantry weapons like medium mortars and heavy machine-guns were rare, though encountered more frequently in external ops late in the war; so much that these heavy weapons had a definite effect on Rhodesian policy and strategic planning.
Split into simpler sentences: Heavier infantry weapons, like medium mortars and heavy machine-guns, were rare though encountered more frequently in external ops late in the war. So much that these heavier weapons had a definite effect on Rhodesian policy and strategic planning.