I need not labour the point which the unbroken testimony of history from the time of the Norman Conquest has established, that all attempts to invade England have been made in the past and must be made in the future across a sea not commanded by the intending invader. If he has secured the command of the sea beforehand, there is nothing to prevent the invasion except the consideration that he can attain his end--that is, the subjugation of the nation's will--at less cost to himself. That being premised, let us consider how the intending invader will set about his task. There are three ways, and three ways only. First, he may seek to overpower the British naval defence on the seas, that is to obtain the command of the sea. If he can do that, the whole thing is done. Or secondly, he may collect the military forces destined for the invasion in ports suitable for the purpose, and when all is ready he may cover their embarkation and transit by a naval force sufficient to overcome any naval force which this country can direct against it. I have already shown, however, that a force sufficient to do this with any certainty, or even with any reasonable prospect of success, must needs be more than sufficient to overpower the British naval defence and thereby to secure the command of the sea, if the enemy were freed from the entangling and wellnigh disabling necessity of providing for the safe conduct of an unwieldy host of otherwise defenceless transports. In other words he is putting the cart before the horse, a procedure which has never yet succeeded in getting the cart to its destination. This second alternative is then merely a clumsy and extremely inefficient way of attaining the same end as the first, and need only be mentioned in order to exclude it from further consideration.