On 25 November 1808, Sir John Moore was asked by the Secretary of State for War for his opinion on the practicality of defending Portugal against the French. Moore, then the Commander-in-Chief of the British Army in Spain and the man considered by many to be Britain's most accomplished General, answered: 'I can say generally that the frontier of Portugal is not defensible against a superior force. It is an open frontier, all equally rugged, but all equally to be penetrated. If the French succeed in Spain it will be vain to attempt to resist them in Portugal. The Portuguese are without a military force ... no dependence can be placed on any aid that they can give. The British must in that event, I conceive, immediately take steps to evacuate the country. Lisbon is the only port, and therefore the only place from whence the army, with its stores can embark .... We might check the progress of the enemy while the stores are embarking, and arrangements are being made for taking off the army. Beyond this, the defence of Lisbon or of Portugal should not be thought of. [1]

Jumbo Map (slow: 186K)

Just four months later, after the death of Moore at Corunna, Wellington - then still Sir Arthur Wellesley - answered the same question put to him by the same minister, Lord Castlereagh. 'I have always been of opinion that Portugal might be defended, whatever might be the result of the contest with the French. My notion was that the Portuguese military establishment ought to be revived, and that in addition to these forces, 20,000 British troops should be employed, including about 4,000 cavalry. My opinion was that, even if Spain should have been conquered, the French would not be able to overrun Portugal with a smaller force than 100,000 men. [2]

Wellington was given the opportunity to prove his theory 'unfettered by any particular instructions which might embarrass him in the execution of his general plan of operations. [3]

His command of the British army gave him a free hand, and almost unlimited powers over the Portuguese. With the eventual control of the British subsidy to the Portuguese government, Wellington began to put into effect one of the most extensive defensive policies known to history.

To fully appreciate Wellington's plans, an examination of the military geography of Portugal as it existed in 1810, and of the current state of the Peninsular War, is essential.

French Invasion of Portugal Part 1: Wellington's Plans for the Defence of Portugal

Introduction
The Military Geography of Portugal
The Situation in 1810 and Fortresses
The Devastation of the Countryside and Footnotes