In the early nineteenth century, the British Navy ruled the waves.
Napoleon may have have been the master of continental Europe, but he didn't
do nearly so well on the high seas. Under Admiral Nelson, the British
reigned supreme, but there was a problem. The British fleet
couldn't be everywhere at the same time without spreading themselves too
thin. They just didn't have enough ships.
In 1804, the British Admiralty placed 120 sailors with canons and all their
gear on Diamond Rock, a small island located three kilometers off the
southern coast of Martinique. This Island was crewed by the British
Navy, and designated as a fighting ship, the unsinkable HMS Diamond Rock.
For seventeen months, the Diamond Rock fired its canons at any French
shipping that foolishly wandered within range.
The steep sides of this inhospitable volcanic rock made it easy to defend
and difficult to conquer. The British occupied the rock for a year and
a half before the French navy evicted them.