Probably the Spanish region with more blue eyed people among its population is Galicia, in the very north west.
That your ancestors fought for Napoleon is not so strange, since the Napoleon’s troops included many forced soldiers from the countries invaded by the French troops, and many mercenaries too.
Spain has given many mercenaries to foreign Armies along its history. And Galicia, since it is one of the poorest regions of Spain give many, many mercenaries, together with Extremadura (where there are also usual the blue eyed people, and from Extremadura come many conquistadors, like Pizarro or Hernán Cortés)