From the onset of the eleventh century, the world was a mass battlefield, and it was the castle that evolved into the mainstream method of fortification and defense. So easily constructed and so simply adequate, the castle came to signify the opening move in the real-world game of chess that prevailed in the later middle ages. Because castles were so adept at fending off attacks, and the high cost of both maintaining a field army and the repercussions of losing a massed army in battle, siege warfare eventually became so much the norm as to almost defunct open battle completely. …