After France had succesfully ousted
Austria,
Russia and
Prussia
in the
fight for dominance of continental
Europe, only
Britain remained as a
serious contender. And indeed, through the victory at
Trafalgar in
1805,
Lord Nelson had secured the
British Isles from the threat of invasion.
Emperor Napoleon Bonaparte instead turned his attention to Spain. In
1807 over 100.000
french soldiers marched over the Spanish border under the pretext that
they were on their way to invade Portugal. The real goal was to
depose the Spanish monarch Fernando VII, and instead put the
Emperor's brother, Joseph Bonaparte,
on the throne. This
resulted in a massive uprising however, which caused Britain to ally
itself with its former enemy Spain and send troops of its own to the
Iberian Peninsula.
The British expeditionary force landed in Portugal in August
1808 and through winning the Battle of Vimeiro managed to force
the French army to evacuate the country. After two years of fighting
and losses on both sides, the French eventually tried to retake
Portugal in September 1810. Wellington, who commanded the British
forces, was pushed back to Torres Vedras, where the fighting came to a
standoff. When fresh reinforcements arrived in May 1811 he was able to
force the French out of Portugal once again.
In the beginning of 1812 the British army attacked Spain, aided
by both Spanish regular and guerilla forces. The French were
experiencing problems on the eastern front, where the invasion of
Russia had failed and Prussia had risen and allied with Russia. This
meant no reinforcements to the western front. Wellington had no such
problems however, and in June 1813 won a decisive victory at
Vitoria. At this time, Austria once again entered the war against
France. Things were starting to look rather bleak for Napoleon.
British troops entered France in October. The French defence was
formidable, but Paris was captured at last in March 1814. Napoleon
abdicated unconditionally on April 11 and was exiled to the island
of Elba.
A lot of information taken from www.peninsularwar.org, a
site which I heartily recommend.