Explanation: Catholic Spain went through the 80 Years’ War trying desperately to hold onto the Netherlands, against the wishes of the largely Protestant population who lived there. Other than the Netherlands developing a formidable navy, they also used the native terrain and infrastructure of the Netherlands to their advantage - including incidents of controlled flooding to stall or disrupt Spanish armies.

One expects a few Spanish veterans came out with a severe case of hydrophobia…

Eighty Years' War - Wikipedia