This question is inspired by just having viewed the trailer for the film "Libertador." Having noticed the actor Iwan Rheon (playing Daniel Florence O'Leary), I found myself reading up on the Irish military diaspora and the British Legion.
But what I wondered, and could not find with some light googling, was whether any Americans from the fledgling North American nation were inspired by republican zeal to travel south and fight against the Spanish.
The idea does not seem too strange. I'm aware of later Americans who were inspired to fight against the fascists in the Spanish Civil War, or the foreign volunteers who fought in both World Wars before the USA officially became a belligerent.
Or maybe it wasn't liberal fervor akin to Lord Byron: maybe they were men motivated by money or adventure like Alexander Gardner (who fought in Afghanistan in the 19th century).
Whether driven by love of liberty, money, or boredom, were any USA citizens fighting on either side during the Spanish American wars of independence?
David Burnet fought under Franciso De Miranda (who had fought in the American Revolution, French revolution, and Wars of Latin American Independence) in the early 19th century. He would later become a fairly prominent political figure in the Republic of Texas.