The Holy Roman Empire, also known as the Holy Roman Empire of the German Nation after 1512, was a polity in Central and Western Europe, usually headed by the Holy Roman Emperor. It developed in the Early Middle Ages (beginning in either 800 or 924), and lasted for a millennium until its dissolution in 1806 during the Napoleonic Wars. Initially, it comprised three constituent kingdoms—Germany, Italy, and, from 1032, Burgundy—held together by the emperor's overlordship. By the 15th century, imperial governance became concentrated in the Kingdom of Germany, as the empire's effective control over Italy and Burgundy had largely disappeared.
On 25 December 800, Pope Leo III crowned the Frankish king Charlemagne Roman emperor, reviving the title more than three centuries after the fall of the Western Roman Empire in 476. The title lapsed in 924, but was revived in 962 when Otto I was crowned emperor by Pope John XII, as Charlemagne's and the Carolingian Empire's successor. From 962 until the 12th century, the empire was one of the most powerful monarchies in Europe. It depended on cooperation between emperors and vassals; this was disturbed during the Salian period. The empire reached the apex of territorial expansion and power under the House of Hohenstaufen in the mid-13th century, but overextension led to a partial collapse. The imperial office was traditionally elective by the mostly German prince-electors. In theory and diplomacy, the emperors were considered the first among equals of all of Europe's Catholic monarchs.
