The evolution of medals struck to commemorate, and later to reward participants, in battle or campaign was a gradual process. The forerunner to the modern campaign medal was the Armada medal, which was awarded after the abortive Spanish invasion of 1588. Initially official campaign medals were only awarded to high-ranking officers. The first medal awarded to all ranks of the Army was the Waterloo medal, issued in 1816.
By the 19th century campaign medals became common place and were awarded for the large number of military campaigns that took place during the time that Britain became the dominant world superpower. Campaign medals were usually issued with clasps which identified the particular battles and engagements the receipient had taken part in. For example the Naval General Service Medal had no fewer than 230 different clasps that could be issed with the medal.