The Peninsular War (1807–1814) was a military conflict between Napoleon's empire and the allied powers of Spain, Britain and Portugal for control of the Iberian Peninsula during the Napoleonic Wars. The war started when French and Spanish armies invaded and occupied Portugal in 1807, and escalated in 1808 when France turned on Spain, its ally until then. The war on the peninsula lasted until the Sixth Coalition defeated Napoleon in 1814, and is regarded as one of the first wars of national liberation, significant for the emergence of large-scale guerrilla warfare.