ABSTRACT
THERE are also certain castles in northern lands which by their natural defences are thought to be invincible. This is because of the difficulty of approach, so that not only is it impossible to attack them directly, but they cannot be overcome by fire nor by the crafty stratagems that provide short cuts in war. The principal cause of this is that, when the defenders have also employed the labours of their skill, Nature's defence creates an impregnable fortress, especially under an active leader, whose subtlety and shrewdness are normally rated highly in hard-fought wars.
