Complex sentence: The Afghanistan Medal was awarded to members of the British and Indian armies who served in Afghanistan between 1878--1880 during the Second Afghan War, the first war being from 1839--1842.
Split into simpler sentences: The Afghanistan Medal was awarded for the military actions involving the British Army and local Indian units in Afghanistan between 1878--1880. This was the Second Anglo-Afghan War, the first being from 1839--1842.