Charlemagne (r.768-814 CE) undertook an unprecedented fifty-four military campaigns during his forty-six-year reign, greatly expanding the territory of the Frankish kingdom he inherited into the Carolingian Empire through the use of an adroit grand strategy. His impressive military and political achievements even won him the title of “emperor of the Holy Romans” from the papacy on Christmas Day, 800 CE, the first of its kind in Western Europe since the fall of Rome three hundred years earlier. Even during his lifetime, he was referred to as “Rex, pater Europa” or “King, father of Europe” based on the large territory brought under his imperium, an area roughly corresponding to modern France, Switzerland, Belgium, the Netherlands, Germany, and parts of Austria, Spain, and Italy. But Charlemagne stood on the shoulders of other great Frankish kings and commanders, who created the foundations of a Frankish kingdom from the ruins of Roman Gaul.  

Only one of the Germanic kingdoms on the European continent, the Frankish kingdom, proved enduring after the fall of the Western Roman Empire in 476. The Franks emerged as a confederation of smaller tribes in the third century in the regions north and east of the Rhine River, crossing south into Roman Gaul in 357 and settling in lands granted to them by the Roman Emperor Julian the Apostate (r.361-363). The first important Frankish dynasty, the Merovingians (c.450-754), produced their first great king, Clovis I (r.481-511) who conquered rival Frankish kings and most of Roman Gaul before his death in 511. His conversion to Roman Catholicism in 496 created a strong alliance with the papacy in Italy, assisting the Roman Catholic Church in its efforts to convert both pagan and Arian Christian (a competing form of Christianity popular with Germanic peoples seen as a heresy by Roman Catholicism and Greek Orthodoxy). However, Merovingian kings after Clovis retreated to court life, leaving day-to-day ruling responsibilities to their major domus or “mayors of the palace.” The most important of these mayors of the palace, Charles Martel (686-741) was the de facto ruler of Frankish lands for more than two decades (718-741), although he was never crowned king. Charles Martel is remembered for his victory over a Muslim expeditionary force at the battle of Tours in 732, and for his ability to consolidate his own power over the region devastated by this Islamic incursion.  Martel’s son, Pepin the Short (r.751-768) would become king of the Franks in 751 through a quid pro quo arrangement with the papacy in exchange for military assistance in Italy against the Lombards, becoming the first of the Carolingian dynasty (751-987) that would witness his son, Charles I, remembered as Charles “the Great” or Charlemagne come to the throne and carve out a unified Roman Catholic kingdom and then empire encompassing most of Western Europe.

Charlemagne’s campaigns took him to many areas in Europe. In 773, he led his army into Italy, crushing the Lombards and crowning his son king of Italy. Four years later, Charlemagne crossed the Pyrenees into northern Spain. However, this campaign proved disappointing. Despite the annihilation of his rearguard at Roncesvalles by the Basques in 778, Charlemagne and his successors were successful in eventually establishing the Spanish March, a string of fortifications in Catalonia which served as a defensive bulwark against Muslim raiding and a future base of operations for the Christian reconquest of Spain (the Reconquista) beginning in the eleventh century.

Charlemagne was more successful in his eastern campaigns into Germany. In 787, he invaded Bavaria and brought that region under his rule. In 790, his Frankish armies marched east along the Danube and met and utterly eradicated the Avar Empire in the Balkans, seizing wealth accumulated in two centuries of raiding and adding it to his own treasury. Perhaps Charlemagne’s greatest success came in Frisia and Saxony, a region in northern Germany between the Rhine and Elbe Rivers. Beginning in 772, Charlemagne set his sight on the conquest and conversion of these regions, but resistance was fierce (Charlemagne campaigned in Saxony in 772, 785, 792-793, and 798-803). In response, Charlemagne ordered in 782 the execution of 4,500 Saxon prisoners (known as the “Massacre at Verden”), the most controversial event of his reign and sparking three years of intense rebellion. It was not until 804, after years of annual campaigns, that Saxony was finally pacified and added to the Carolingian domain.   

While creating this new imperium in Western Europe Charlemagne never developed a regular standing army; instead, he relied on feudal levies to raise his forces, creating a small army compared to the armies of the classical period (modern estimates vary from 5,000 to 35,000 men, excluding attendants). It did not take the emperor long to assimilate new regions into his military machine. Just two years after bringing Saxony into the kingdom, Charlemagne created a sliding scale of military contributions, ordering five Saxon vassals to equip a sixth to campaign in Spain, two to equip a third for Bohemia, while all were required to campaign against regional threats. In 807, he issued a capitulary decreeing all nobles in the realm holding a benefice (a lease of land) were obligated to military service. If a noble failed to muster for war, he risked the confiscation of his estate. Charlemagne perfected this system to the point where he could raise several annual levies and conduct operations on multiple fronts, including Germany, Bohemia, Brittany, and Spain.

Charlemagne’s military success was not founded on decisive engagement; indeed, history only records him present at three battles during his lengthy reign. The Carolingian emperor’s success was instead based on a well-trained and experienced feudal fighting force wearing down the enemy through a strategy of attrition and the ability to raise several armies for annual campaigns in different regions. He also recognized the impending threat to his empire, building and garrisoning forts along his borders with the Muslims, Danes, and Slavs. He even went so far as to try and maintain his superiority in military equipment by threatening the forfeiture of all property to anyone selling mail hauberks to foreigners and death to any who exported Carolingian swords out of the country (weapons favored by the Vikings because of their quality). The composition and equipment of Charlemagne’s army was continuously evolving. Initially, the Carolingian army comprised mostly of infantry, but as campaigning took him farther and farther from his base in Austrasia, Charlemagne soon relied increasingly on mounted troops over infantry. His numerous capitularies (imperial edicts) point to the raised status of cavalry. Between 792-793, he issued regulations requiring vassals to have a horse, shield, lance, sword, dagger, bow, quiver, and arrows. In other royal decrees wealthier nobles were ordered to come to war wearing mail and were asked to bring rations for three months of service and clothing for six. Furthermore, these greater magnates were to make certain their own vassals came on campaign with a standardized panoply consisting of shield, spear, bow and twelve arrows. Even attendants were required to be armed with bows.

Finally, Charlemagne’s greatest military legacy was his emphasis on cavalry as an instrument of strategic mobility. And though the stirrup-stabilized lancer, probably present in limited numbers during Charlemagne’s reign, did not revolutionize battle tactics in the late eighth and early ninth centuries, heavy cavalry’s importance as the centerpiece of the Carolingian tactical system was a harbinger of how war would be made in the later medieval period, a type of equestrian-based warfare centered around the mounted knight.

Suggested Readings:

Primary sources

Einhard and Notker, Two Lives of Charlemagne. Edited and translated by David Ganz. Penguin, 2008.

Secondary sources

Bachrach, Bernard S. Armies and Politics in Early Medieval West. Aldershot, 1993.

Beeler, John. Warfare in Feudal Europe, 730-1200. Cornell University Press, 1971.

Bowlus, C.W. Franks, Moravians, and Magyars: The Struggle for the Middle Danube, 788-907. University of Pennsylvania Press, 1995.

Ganshof, F.L. Frankish Institutions under Charlemagne. Brown University Press, 1968.