The Napoleon Series
An excellent resource dedicated to the study of the life and times of Napoleon Bonaparte, with articles on campaigns and battles and collection of maps.
The Napoleonic Association
Founded over 30 years ago, the Napoleonic Association has Research, Re-enactment and Wargaming sections.
USMA Department of History
With maps of the campaigns of June to August 1808 and October 1808 to January 1809.
Memorial at Peninsula
Tribute at Peninsula Barracks, the ancestral home of the Green Jackets.
Ian Fletcher Battlefield Tours
Although a commercial site, Ian's archive page links to many interesting articles on the Peninsular War.
Peninsular War blog (in Portuguese).
Los Sitios de Zaragoza
Detailed description of the two French sieges of the Spanish-held city of Zaragoza in 1808-9.
Short Barrels and Long Bumpers
Sue Law's pages on the 95th (Rifle) Regiment of the British Army during the Napoleonic Wars.
Guerra de la Independencia Española, 1808-1814
Another Spanish perspective on the Peninsular War.
The National Archives
TNA information leaflets British Army: Campaign Records, 1714-1815 and British Army: Soldiers' Discharge Papers, 1760-1913 are available on-line.
Directory of Military Museums and other places of military interest in the UK.