The Napoleonic Wars were a series of wars declared against Napoleon's French Empire by opposing coalitions that ran from 1803 to 1815. As a continuation of the wars sparked by the French Revolution of 1789, they revolutionised European armies and played out on an unprecedented scale, mainly due to the application of modern mass conscription. French power rose quickly as Napoleon's armies conquered much of Europe but collapsed rapidly after France's disastrous invasion of Russia in 1812. Napoleon's empire ultimately suffered complete military defeat resulting in the restoration of the Bourbon monarchy in France.
The wars resulted in the dissolution of the Holy Roman Empire and sowed the seeds of nascent nationalism in Germany and Italy that would lead to the two nations' individual consolidation later in the century. Meanwhile, the global Spanish Empire began to unravel as French occupation of Spain weakened Spain's hold over its colonies, providing an opening for nationalist revolutions in Spanish America. As a direct result of the Napoleonic wars, the British Empire became the foremost world power for the next century, thus beginning Pax Britannica.
No consensus exists as to when the French Revolutionary Wars ended and the Napoleonic Wars began. An early candidate is 9 November 1799, when Bonaparte seized power in France with the coup of 18 Brumaire. 18 May 1803 is the most commonly used date, as this was when a renewed declaration of war between Britain and France (resulting from the collapse of the Treaty of Amiens), ended the only period of general peace in Europe between 1792 and 1814. The Napoleonic Wars ended following Napoleon's final defeat at Waterloo on 18 June 1815 and the Second Treaty of Paris.