The details are scant, but I hope it's enough to get the community interested and a clear answer emerge (there can't be that many people who fit the bill?).
I read a long time ago about a famous Spanish/Latin American soldier who fought in several major conflicts in the 18th or 19th century: he fought in Latin America (maybe with Jose de San Martin?), in the US, and in Europe. I'm not clear if he was a mercenary of sorts, or just chased after battle, but I remember being amazed at the fact that this one man managed to be a part of the major military conflicts at the time.
I'm hoping to find a good biography--I know it exists because I read about this person in a major media company: something like 'the not-so-famous soldier/general that shaped world history' (very loose paraphrase). At the time I found some books on Amazon but life happened and I lost track of them.