Notwithstanding his failure to appreciate all the difficulties of naval warfare, the Great Emperor had grasped one of its leading principles.  Before the Peace of Amiens, indeed before his campaign in Egypt, and even his imposing triumphs in Italy, he had seen that the invasion of the United Kingdom was impracticable without first obtaining the command of the sea.  His strategic plan, therefore, included arrangements to secure this.  The details of the plan were changed from time to time as conditions altered; but the main object was adhered to until the final abandonment of the whole scheme under pressure of circumstances as embodied in Nelson and his victorious brothers-in-arms.  The gunboats, transport boats, and other small craft, which to the number of many hundreds filled the ports of north-eastern France and the Netherlands, were not the only naval components of the expedition.  Fleets of line-of-battle ships were essential parts of it, and on their effective action the success of the scheme was largely made to depend.  This feature remained unaltered in principle when, less than twelve months before Trafalgar, Spain took part in the war as Napoleon’s ally, and brought him a great reinforcement of ships and important assistance in money.

We should not fail to notice that, before he considered himself strong enough to undertake the invasion of the United Kingdom, Napoleon found it necessary to have at his disposal the resources of other countries besides France, notwithstanding that by herself France had a population more than 60 per cent. greater than that of England.  By the alliance with Spain he had added largely to the resources on which he could draw.  Moreover, his strategic position was geographically much improved.  With the exception of that of Portugal, the coast of western continental Europe, from the Texel to Leghorn, and somewhat later to Taranto also, was united in hostility to us.  This complicated the strategic problem which the British Navy had to solve, as it increased the number of points to be watched; and it facilitated the junction of Napoleon’s Mediterranean naval forces with those assembled in his Atlantic ports by supplying him with allied ports of refuge and refit on Spanish territory—­such as Cartagena or Cadiz—­between Toulon and the Bay of Biscay.  Napoleon, therefore, enforced upon us by the most convincing of all arguments the necessity of maintaining the British Navy at the ‘two-power standard’ at least.  The lesson had been taught us long before by Philip II, who did not venture on an attempt at invading this country till he was master of the resources of the whole Iberian peninsula as well as of those of the Spanish dominions in Italy, in the Burgundian heritage, and in the distant regions across the Atlantic Ocean.