Estimates of 50,000 to 60,000 Spanish troops crossing the Channel ignore the cost to Spain's other fronts. Moving that force would leave the Netherlands with few troops and effectively no mobile army. Unrest there continued while France and territories of the Holy Roman Empire could also create pressure. The invasion plan competed with those continental commitments, so available shipping was only one limit on the army Philip II could responsibly move.
Notable Point · 31:52-32:48
A larger invasion army would expose Spain's other fronts
Moving 50,000 to 60,000 Spanish troops across the Channel would have stripped mobile forces from the Netherlands amid pressure from France and the Holy Roman Empire.