Coalitions versus Napoleon remade Europe from 1803 to 1815
The Napoleonic Wars (1803–1815) pitted shifting European coalitions against France under the Consulate and then the Empire. Britain declared war on 18 May 1803, later aligning with Austria, Russia, and smaller states in campaigns that went global.
The fighting grew out of the French Revolution and the Revolutionary Wars of 1792–1802, and historians split it into seven wars: five named after the coalitions that faced Napoleon, from the Third to the Seventh, plus the Peninsular War and the invasion of Russia. Britain opened hostilities in May 1803 and by April 1805 had joined Austria and Russia in the Third Coalition. French triumphs at Ulm and Austerlitz dissolved the Holy Roman Empire and knocked Austria out. Prussia entered the Fourth Coalition in October 1806, only to be crushed at Jena-Auerstedt, while Russia lost at Friedland, so the continent settled into an uneasy peace by July 1807. At sea, however, Trafalgar handed Britain mastery.
Unable to beat Britain on the water, Napoleon turned to economic strangulation through his Continental System. That pulled him into Portugal, Britain's last foothold on the mainland, and Lisbon fell in November 1807. He then betrayed Spain, removed its royal family and crowned his brother Joseph in 1808, igniting the Peninsular War. Austria seized the moment to form the Fifth Coalition in April 1809; it won at Aspern-Essling but lost at Wagram and accepted a punishing peace that October.
The unravelling began when Russia, hurt by lost commerce, broke the blockade. Napoleon invaded in June 1812 and his Grande Armée was nearly annihilated, pulling back by December. A Sixth Coalition beat him at Leipzig in October 1813, took Paris in March 1814 and sent him to Elba. He escaped in February 1815 for roughly a hundred days before defeat at Waterloo that June and final exile on Saint Helena, where he died in 1821.
The consequences reached well beyond the battlefield. Mass conscription and guerrilla fighting entered the military repertoire, the civil law of the Napoleonic Code was largely kept wherever it had taken root, and nationalism and liberalism spread. Spanish America's independence movements arose directly from the upheaval, hastening Iberian imperial decline, and Britain emerged as the leading naval and economic power for the rest of the century. The Congress of Vienna redrew the map, and no great-power war erupted again until Crimea in 1853.
Source: Napoleonic Wars
