The Germans had realized from the start a vital difference between war on sea and war on land. The land affords some protection to the weaker combatant especially on the defensive; the sea gives none. There are no trenches in the sea, but only graves. It is merciless to the vanquished, and the casualties in a beaten fleet are total losses; instead of prisoners, fugitives, and wounded, there is one vast list of drowned. Ships that are sunk do not return to the battle-line, and their loss takes long to repair. Years are required to build a Dreadnought, and years to make a seaman. Armies are easier to create and more difficult to destroy than fleets, and the sailor's fight is ever one to a finish, with little chance of escape from the dread alternative. It is a case of all or nothing; there are no water-tight compartments in sea-power, no fluctuating spheres of power, no divided areas in some of which one and in some the other combatant may be supreme. Apart from land-locked waters the sea is one and indivisible, and he who has the command, commands it everywhere. The battle at sea is a battle without a morrow for those who lose; and from the day when the Germans wisely withdrew into Kiel and Wilhelmshaven there was little chance that they would come out to fight to a finish except as a counsel of despair or until they could by mine or submarine or skilful raid reduce the disparity of force. That was the purpose of their early naval strategy; it proved ineffective owing to British skill and caution, and it became hopeless when it appeared that we could build ships much faster than the Germans could sink them or build ships themselves; and the Germans then turned from the task of destroying the British Navy to that of destroying the commerce on which we depended for subsistence, from the hope of securing the command of the sea for themselves to that of turning it into a "no man's land," a desert which no allied or neutral ship could cross.