Napoleon's occupation of the Iberian peninsula embroiled him in a protracted and costly war against British, Spanish and Portuguese forces ultimately led by one of history's greatest commanders -- the Duke of Wellington. Yet it also introduced a new dimension to warfare, for Napoleon's 'Spanish ulcer' became a bitter seven-year struggle against peoples inflamed by nationalism. Thus, while Wellington achieved successive victories in open battle, a parallel guerrilla war exacted a heavy toll of its own on the invaders. No mere sideshow to the other campaigns of the period, the Peninsular War made a significant contribution to Napoleon's eventual downfall.

Gregory Fremont-Barnes holds a doctorate in Modern History from the University of Oxford. As a Senior Lecturer in the Department of War Studies at the Royal Military Academy, Sandhurst, he has written extensively on a range of subjects covering military affairs since the 18th century. In addition to teaching cadets, he travels widely for the Ministry of Defence, running courses for foreign military and intelligence officers, and spent two years in Afghanistan on Operation Toral.