The Spanish Main: Tales of the Union Jack, the Fleur-de-Lis and the Jolly Roger

Have you ever wondered why there are so many old-time forts on the Caribbean islands? And who built them? And why?

You'll spot forts just about everywhere on the old "Spanish Main" - meaning all the Caribbean islands and the countries rimming them along the coasts of Central and South America. Some are jumbo-size, like the $2 trillion monster fort overlooking the Colombian harbor of Cartagena, where treasure galleons gathered to sail in convoys to Spain. Other forts, like those perched on some of the hilltops in the Grenadines, boast just a cannon or two.

Spanish super-fort guarded treasure fleets at Cartagena, Colombia.

Most of the forts were built during the 17th and 18th centuries when Spain, France, England and The Netherlands were slugging it out to grab islands to grow sugarcane, tobacco, cotton and the like. Not only did all these countries have to keep an eye out for each other's ships, but also for guys with eye patches sailing around under the flag of the Jolly Roger.

At one time hundreds of pirates roamed the Caribbean, hoping to bag slow-moving cargo ships (whether they flew the colors of Spain, England, France or anyone else). When they couldn't find any merchant ships to loot, they settled for plundering lightly defended ports.

Ancient cannons stand silent vigil on St. Croix, U.S. Virgin Islands.

Sometimes the colors of different nations flew over the same forts at different times. For instance, during a long series of wars between France and England, France's Fleur-de-lis went down and England's Union Jack went up on the island of St. Lucia seven times before France finally threw in the towel in 1814.

Photo from Jade Mountain shows volcanic peaks soaring over St. Lucia.

"The War of Jenkins Ear" was another big flag-changer. This one started off the coast of Florida in 1731 when a Spanish ship captured a British merchant vessel commanded by Robert Jenkins. For some reason, the Spanish commander cut off one of Jenkins' ears.

Now, the Brits could hardly take that insult lying down, so - after one thing led to another (including bickering over the rights to sell slaves in the Caribbean) - they ended up declaring war on Spain. In one battle, an English fleet led by Admiral Edward "Old Grog" Vernon captured and sacked the wealthy Spanish port at Portobello, Panama. Flushed with success, Vernon went on to attack another big Spanish port down the coast at Cartagena - and literally ran into a stone wall at the mega-fort there. Vernon showed up with a force of 23,000 men and 186 ships bristling with 2,000 cannons, but the fort, defended by just 3,000 Spanish troops and six ships, sent Old Grog packing after a month-long siege of the city.

Cannons dot the hilltops of St. Vincent and the Grenadines.

And so it went over the years, until the mid-1700s when piracy fizzled out and the forts had a little less to do. But what put them out of business was an all-hands summit of the European powers in 1815, at the end of the Napoleonic wars. Called the Congress of Vienna, the pact divvied up Europe to the likes of the big players in return for everyone's promise to behave.

And as Europe went, so did the Caribbean, with certain islands going to the English, French, Spanish and Dutch. Most of the islands have since gained their independence, semi-independence, or fewer ties to their overseas parent countries.

Family poses on a cannon that once blasted enemy ships.

All those ancient forts, once bristling with cannons manned by sharp-eyed gunners, are now full of tourists scampering around their ramparts and posing for pictures on the cannons.

All photos by Bob Schulman.