Spain's units are a well-blended mix of skirmishers, excellent swordsman, spearmen and pikemen, and a decent cavalry. Their gunpowder units are also highly advanced and deadly. Spain is also a very strong Naval Power faction. they are also the only Southern European Faction along with Portugal to have a Northern European ship - the Cog as their first Naval Ship. This is due to the rough Atlantic Ocean near Spain and Portugal.
Spain's units early on in the game have a poor selection of Infantry with militia and Javalinmen being the best choices. Later on however they start to gain heavy infantry, like dismounted Feudal Knights, dismounted Chivalric Knights, sword and buckler men and dismounted conquistadores.
With Spain's position near the Moors and Portugal it is quite clear for the player that the Reconquista must commence and the re-conquest of Spanish lands from the Muslim Moors must be at hand early on in the game. This is a great conflict for the player if he or she is to succeed as this will grant rich territories and Papal favor. It would be recommended to the player after kicking out the Moors and consolidating their position on the whole of the Iberian Peninsula that they should march south into North Africa and conquer the riches their for the Glory of Spain and to get even with the Moors.
Spain's starting regions even allow them to expand into eastern France, where mainly it is only rebel-provinces. This could make way for more powerful units, allowing Spain to attack Britian and finally finishing off the Moors.
Historically Spain did succeed in the Reconquista brilliantly, lasting well off into the 1400's. They would go on to conquer most of the Americas and be the first Europeans to gaze upon the Pacific, their culture and language still thrives in the colonies they established.