For three years public opinion in England had been divided, some sustaining on the one hand Canning's policy of striving to defeat Napoleon by rousing the Continental nations and furnishing them with subsidies for warfare, others preferring that of Castlereagh, which advocated the sending of English forces into the Continent. The latter theory had temporarily prevailed. Three expeditions, one to Portugal, one to Walcheren, and one to Sicily, had been entire or partial failures. But Wellington's victory at Talavera having kept the peninsular ports open to English trade, his older brother, Lord Wellesley, who was now secretary for foreign affairs in the new cabinet, and who ardently believed that thus alone could England win, managed continuously to reinforce the army in Portugal until at last it was strong in numbers and efficient as a fighting machine.
From beginning to end Masséna's campaign was marked by unexpected disaster. Such were the zeal and endurance of the Spaniards that the old, ill-constructed fortress of Ciudad Rodrigo held out from the beginning of June until the ninth of July. Owing to the great heat and the preparations necessary in a hostile and deserted land, Almeida, which next blocked the way, was not even beleaguered until August fifteenth, and it held out for nearly a fortnight. Finally, on September sixteenth, Masséna crossed the Portuguese frontier, and Wellington, who lay near by but had not ventured to assume the offensive, began a slow and cautious retreat down the valley of the Mondego, devastating the country as he went. At last he made a stand on the heights near Busaco, over against a gorge where the river breaks through the hills into the plains below. Masséna attacked on September twenty-seventh and was repulsed with a loss of four thousand five hundred dead and wounded. His division commanders showed at once a spirit which soon developed into unruliness: they had declared from the outset that their force was not sufficiently strong for the task assigned to it, and they now demanded a retreat. But the veteran Masséna stood firm: his scouts had brought word of a certain unprotected vale or rather depression of the land on the English left, which, having apparently escaped Wellington's observation, was not fortified, and the French commander determined to outflank his foe on that line. The movement was thoroughly successful and the British began a rapid retreat southward before the advancing French.