At age 26, he began his first military campaign against the Austrians and the Italian monarchs aligned with the Habsburgs—winning virtually every battle, conquering the Italian Peninsula in a year while establishing "sister republics" with local support, and becoming a war hero in France.
In 1798, he led a military expedition to Egypt that served as a springboard to political power.
France then forced the defeated nations of the Fourth Coalition to sign the Treaties of Tilsit in July 1807, bringing an uneasy peace to the continent.
Tilsit signified the high-water mark of the French Empire.
Intractable differences with the British meant that the French were facing a Third Coalition by 1805.
Napoleon shattered this coalition with decisive victories in the Ulm Campaign and a historic triumph over the Russian Empire and Austrian Empire at the Battle of Austerlitz which led to the dissolution of the Holy Roman Empire.
The Spanish and the Portuguese revolted with British support.
The Peninsular War lasted six years, featured extensive guerrilla warfare, and ended in victory for the Allies against Napoleon.
In 1809, the Austrians and the British challenged the French again during the War of the Fifth Coalition, but Napoleon solidified his grip over Europe after triumphing at the Battle of Wagram in July.
Napoleon then invaded the Iberian Peninsula, hoping to extend the Continental System and choke off British trade with the European mainland, and declared his brother Joseph Bonaparte the King of Spain in 1808.