Spain played a major role in the US War of Independence, most notably there were two generals who distinguished themselves during that war: Bernardo de Gálvez (made and honorary citizen by Washington, but the motion was forgot and only passed into law in 2014) and Luis de Córdova.

Bernardo de Gálvez, first Count of Gálvez and first viscount of Galveston, organised a succesful campaign that recovered Mobile, Pensacola, the coast of Florida, and took control of the Bahama channel acting from his base in Louisiana, of which he was governor. He also granted refuge in Spanish ports to American ships that needed it, and allowed American ships to trade from there. Gálvez also suffocated a rebellion in Natchez, and blockaded New Orleans so that the English ships could not go up the Mississippi to organise a flanking manoeuvre against the American forces. His campaigns secured a Spanish control of the Gulf of Mexico, Florida, and the Bahamas, that made it impossible for the British to reinforce their troops. Gálvez was thanked for his service, made an honorary citizen of the United States, and it was approved to have his portrait in the American Congress. This last part was entirely forgotten until someone realised in 2013, and Gálvez's portrait was eventually hung in 2014. His honorary citizenship was also legally approved by Congress that year.

The old admiral Luis de Córdova y Córdova dealt an enormous blow against the British with his action of September the 9th 1780. In that action, Córdova captured a British double convoy with supplies for the troops that were fighting against the American rebels. The supplies captured amounted to 294 cannons, 80,000 muskets, 3,000 barrels of gunpowder, clothes and equipment for 12 regiments, one million pounds in cash, and 2,934 prisoners. This capture made the war virtually unwinnable for the British, cause the bankruptcy of many insurance companies, and deeply affected the London Stock.

Besides these two generals and their military actions, Spain contributed economically to the American independence cause, though in smaller numbers than France. Beaumarchais and Floridablanca had set up a shell company called Roderigue Hortalez et Compagnie in order to provide money and supplies to the rebels, which were of vital importance in 1776.

These are rather broad strokes on the Spanish participation in the War of American Independence, but there is much bibliography available, at least in Spanish.