Spain has the Conquistador as its unique unit (replacing the Knight). Conquistadors are immune to First Strikes. However, Conquistador has a considerable +50% vs melee units – making it more powerful against Maceman, and a serious threat to Pikeman (even though the latter has +100% with mounted units). In any case, to utilize Conquistadors you should discover Guilds as soon as possible and have control of Horses and Iron.
The starting technologies for the Spanish are Fishing and Mysticism – enabling Sailing right away. It would be also wise to study the immediately available Polytheism or Meditation (founding Hinduism and Buddhism respectively) right away, and afterwards turn to Masonry and Animal Husbandry.
The civilization has only 1 leader - Isabella.