At first the British government were apprehensive of allowing Prince Andrew to remain on Invincible, and wished to move him to a desk job. The prospect of the son of the Queen being killed in action was a possibility, and the government wished to avoid such a circumstance. However, the Queen insisted that Prince Andrew remain with his ship, and so he joined the Invincible as it sailed south, as a Sea King helicopter co-pilot.
In ancient Europe, monarchs were expected to LEAD the people into battle; to sacrifice themselves for the people in the process, if need be. Joan of Arc sacrificed her life in the 1400s because her king would not lead his people in their own self-defense. Another example: even in the 1600s the Kings of Denmark/Norway (Frederick IV, Christian V) were still personally leading their forces into battle.
If this were the case today, do you think war would be still be such a popular sport?