1812. The invasion was an unmitigated disaster for Napoleon; scorched earth tactics, desertion, French strategic failures and the onset of the Russian winter compelled Napoleon to retreat with massive losses. Napoleon suffered further setbacks; French power in the Iberian Peninsula was broken at Battle of Vitoria the following summer, and a new coalition began the War of the Sixth Coalition. The coalition defeated Napoleon at Leipzig, precipitating his fall from power and eventual abdication on 6 April 1814. The victors exiled Napoleon to Elba and restored the Bourbon monarchy. Napoleon escaped from Elba in 1815, gathering enough support to overthrow the monarchy of Louis XVIII, triggering a seventh, and final, coalition against him. Napoleon was decisively defeated at Waterloo, and he abdicated again on 22 June. On 15 July, he surrendered to the British at Rochefort, and was permanently exiled to remote Saint Helena. The Treaty of Paris, signed on 20 November 1815, formally ended the war. The Bourbon monarchy was restored once more, and the victors began the Congress of Vienna to restore peace to the continent. As a direct result of the war, the Kingdom of Prussia rose to become a great power on the continent, while Great Britain, with its unequalled Royal Navy and growing Empire, became the world's dominant superpower, beginning the Pax Britannica. The Holy Roman Empire was dissolved, and the philosophy of nationalism that emerged early in the war contributed greatly to the later unification of the German states, and those of the Italian peninsula. The war in Iberia greatly weakened Spanish power, and the Spanish Empire began to unravel; Spain would lose nearly all of its American possessions by 1833. The Portuguese Empire shrank, with Brazil declaring independence in 1822. The wars revolutionised European warfare; the application of mass conscription and total war led to campaigns of unprecedented scale, as whole nations committed all their economic and industrial resources to a collective war effort. Tactically, the French Army redefined the role of artillery, while Napoleon emphasised mobility to offset numerical disadvantages, and aerial surveillance was used for the first time in warfare. The highly successful Spanish guerrillas demonstrated the capability of a people driven by fervent nationalism against an occupying force. Due to the longevity of the wars, the extent of Napoleon's conquests, and the popularity of the ideals of the French Revolution, the ideals had a deep impact on European social culture.