Had Napoleon been able to reap the fruits of the strife which his policy had thus forced on the two English peoples, it is hard to say how Britain could have coped with him. Cut off from her markets alike in east and west, her industries checked and disorganized, a financial crisis added to her social embarrassment, it may be doubted whether she must not have bowed in the end before the pressure of the Continental System. But if that system had thrust her into aggression and ruin, it was as inevitably thrusting the same aggression and ruin on her rival. The moment when America entered into the great struggle was a critical moment in the history of mankind. Six days after President Madison issued his declaration of war, Napoleon crossed the Niemen on his march to Moscow. Successful as his policy had been in stirring up war between England and America, it had been no less successful in breaking the alliance which he had made with the Czar at Tilsit and in forcing on a contest with Russia. On the one hand, Napoleon was irritated by the refusal of Russia to enforce strictly the suspension of all trade with England, though such a suspension would have ruined the Russian landowners. On the other, Alexander saw with growing anxiety the advance of the French Empire which sprang from Napoleon's resolve to enforce his system by a seizure of the northern coasts. In 1811 Holland, the Hanseatic towns, part of Westphalia, and the Duchy of Oldenburg were successively annexed, and the Duchy of Mecklenburg threatened with seizure. A peremptory demand on the part of France for the entire cessation of intercourse with England brought the quarrel to a head; and preparations were made on both sides for a gigantic struggle.
Even before it opened, this new enterprise gave fresh vigour to Napoleon's foes. The best of the French soldiers were drawn from Spain to the frontier of Poland; and Wellington, whose army had been raised to a force of forty thousand Englishmen and twenty thousand Portuguese, profited by the withdrawal to throw off his system of defence and to assume an attitude of attack. Ciudad Rodrigo and Badajoz were taken by storm during the spring of 1812; and at the close of June, three days before Napoleon crossed the Niemen, in his march on Moscow, Wellington crossed the Agueda in a march on Salamanca. After a series of masterly movements on both sides, Marmont with the French army of the North attacked the English on the hills in the neighbourhood of that town on the twenty-second of July. While he was marching round the right of the English position his left wing remained isolated; and with a sudden exclamation of "Marmont is lost!" Wellington flung on it the bulk of his force, crushed it, and drove the whole army from the field. The loss on either side was nearly equal, but failure had demoralized the French army; and its retreat forced Joseph to leave Madrid, and Soult to evacuate Andalusia and to concentrate the southern army on the eastern coast. While Napoleon was still pushing slowly over the vast plains of Poland, Wellington made his entry into Madrid in August, and began the siege of Burgos. The town however held out gallantly for a month, till the advance of the two French armies, now concentrated in the north and south of Spain, forced Wellington, in October, to a hasty retreat on the Portuguese frontier.