The general principles which should govern the conduct of war at sea and on land have been established by a series of conflicts extending over some hundreds of years. Their correct application leads to success; a divergence from them has too often produced failure. When we find great results following the operations of fleets and armies we consider the leader in each case a genius; an example of this at sea was Nelson - on land Napoleon. Each seemed to grasp intuitively the right thing to do, and did not allow subsidiary considerations to divert him from his main objective.