What mistake did the Royalists?

The Royalists, during the English Civil War, made several strategic mistakes, one of which was underestimating the resolve and organization of the Parliamentarians. They also failed to secure adequate alliances and resources, leading to a lack of support in critical battles. Additionally, their dependence on traditional nobility and outdated tactics hindered their adaptability to the evolving nature of warfare at the time. This combination of miscalculations ultimately contributed to their defeat.