 They also became indispensable in financing the military capability of Habsburg Spain in its long series of European and North African wars, though, with the exception of a few years in the 17th century, Taxes in Castile were the most important source of revenue.Spain enjoyed a cultural golden age in the 16th and 17th centuries.For a time, the Spanish Empire dominated the oceans with its experienced navy and ruled the European battlefield with its fearsome and well trained infantry, the famous "".