The Middle Ages form the middle period in a traditional schematic division of European history into three "ages": the classical civilization of Antiquity, the Middle Ages and Modern Times. The idea of such a periodisation is attributed to Flavio Biondo, an Italian Renaissance humanist historian.
The Middle Ages are commonly dated from the fall of the Western Roman Empire (or by some scholars, before that) in the 5th century to the beginning of the Early Modern Period in the 16th century, marked by the rise of nation-states, the division of Christianity in the Reformation, the rise of humanism in the Italian Renaissance, and the beginnings of European overseas expansion which allowed for the Columbian Exchange. There is some variation in the dating of the edges of these periods which is due mainly to differences in specialization and focus of individual scholars. Commonly seen periodization ranges span the years ca. 400–476 AD (the sackings of Rome by the Visigoths to the deposing of Romulus Augustus) to ca. 1453–1517 (the Fall of Constantinople to the Protestant reformation begun with Martin Luther's 95 theses). Dates are approximate, and are based upon nuanced arguments.
The Middle Ages witnessed the first sustained urbanization of northern and western Europe. Modern European states owe their origins to events unfolding in the Middle Ages; present European political boundaries are, in many regards, the result of the military and dynastic achievements in this tumultuous period.
The Roman empire reached its greatest territorial extent during the 2nd century. The following two centuries witnessed the slow decline of Roman control over its outlying territories. The Emperor Diocletian split the empire into separately administered eastern and western halves in 285. The division between east and west was encouraged by Constantine, who refounded the city of Byzantium as the new capital, Constantinople, in 330. Military expenses increased steadily during the 4th century, even as Rome’s neighbours became restless and increasingly powerful. Tribes who previously had contact with the Romans as trading partners, rivals, or mercenaries had sought entrance to the empire and access to its wealth throughout the 4th century. Diocletian’s reforms had created a strong governmental bureaucracy, reformed taxation, and strengthened the army.
These changes bought the Empire time, but these reforms demanded money. Rome’s declining revenue left it dangerously dependent on tax revenue. Future setbacks forced Rome to pour ever more wealth into its armies, spreading the empire’s wealth thinly into its border regions. In periods of expansion, this would not be a critical problem. The defeat in 378 at the Battle of Adrianople, however, destroyed much of the Roman army, leaving the western empire undefended.
Without a strong army in the west, and with no promise of salvation coming from the emperor in Constantinople, the western Empire sought compromise. Known in traditional historiography collectively as the “barbarian invasions”, the Migration Period, or the Völkerwanderung ("wandering of the peoples") specifically by German historians, this migration of peoples was a complicated and gradual process. Some early historians have given this period the epithet of "Dark Ages".
Recent research and archaeology have also revealed complex cultures persisting throughout the period. Some of these "barbarian" tribes rejected the classical culture of Rome, while others admired and aspired to it. Theodoric the Great of the Ostrogoths, as only one example, had been raised in Constantinople and considered himself an heir to its culture, employing erudite Roman ministers like Cassiodorus. Other prominent tribal groups that migrated into Roman territory were the Huns, Bulgars, Avars and Magyars, along with a large number of Germanic, and later Slavic peoples. Some tribes settled in the empire’s territory with the approval of the Roman senate or emperor. In return for land to farm and, in some regions, the right to collect tax revenues for the state, federated tribes provided military support to the empire. Other incursions were small-scale military invasions of tribal groups assembled to gather plunder. The most famous invasion culminated in the sack of Rome by the Visigoths in 410. By the end of the 5th century, Roman institutions were crumbling. The last emperor of the west, Romulus Augustulus, was deposed by the barbarian king Odoacer in 476.
The Eastern Roman Empire (conventionally referred to as the "Byzantine Empire" after the fall of its western counterpart) maintained its order by abandoning the west to its fate. Even though Byzantine emperors maintained a claim over the territory, and no barbarian king dared to elevate himself to the position of emperor of the west, Byzantine control over the west could not be sustained. For the next three centuries, the region of the former western empire would be without a legitimate emperor. It was, instead, ruled by kings who enjoyed the support of the largely barbarian armies. Some kings ruled as regents for titular emperors, and some ruled in their own name. Throughout the 5th century, cities throughout the empire declined, receding inside heavily fortified walls. The western empire, particularly, experienced the decay of infrastructure which was not adequately maintained by the central government. Where civic functions and infrastructure such as chariot races, aqueducts, and roads were maintained, the work was frequently done at the expense of city officials and bishops. Augustine of Hippo is an example of a bishop who acted as an able administrator. One scholar, Thomas Cahill, has dubbed Augustine the last of the classical men and the first of medieval men.
The Crusades were, in some aspects, Europe's defense against Islamic expansion and aggression. These were armed pilgrimages intended to liberate Jerusalem from Muslim control. Jerusalem was part of the Muslim possessions won during a rapid military expansion in the 7th century through the Near East, Northern Africa, and Anatolia (in modern Turkey). The first Crusade was preached by Pope Urban II at the Council of Clermont in 1095 in response to a request from the Byzantine emperor Alexios I Komnenos for aid against further advancement. Urban promised indulgence to any Christian who took the Crusader vow and set off for Jerusalem. The resulting fervour that swept through Europe mobilized tens of thousands of people from all levels of society, and resulted in the capture of Jerusalem in 1099 as well as other regions. The movement found its primary support in the Franks; it is by no coincidence that the Arabs referred to Crusaders generically as "Franj".
Although they were minorities within this region, the Crusaders tried to consolidate their conquests, as a number of Crusader states – the Kingdom of Jerusalem, as well as the County of Edessa, the Principality of Antioch, and the County of Tripoli (collectively Outremer). During the 12th century and 13th century there were a series of conflicts between these states and surrounding Islamic ones. Crusades were essentially resupply missions for these embattled kingdoms. Military orders such as the Knights Templar and the Knights Hospitaller were formed to play an integral role in this support. By the end of the Middle Ages the Christian Crusaders had captured all the Islamic territories in modern Spain, Portugal and Southern Italy. Meanwhile, Islamic counter attacks had retaken all the Crusader possessions on the Asian mainland, leaving a de facto boundary between Islam and western Christianity that continued until modern times. Substantial areas of northern Europe also remained outside Christian influence until the 12th century or later; these areas also became crusading venues during the expansionist High Middle Ages.
Throughout this period the Byzantine Empire was in decline, having peaked in influence during the High Middle Ages. Beginning with the Battle of Manzikert in 1071, the empire underwent a cycle of decline and renewal, including the sacking of Constantinople by the Fourth Crusade in 1204. Despite another short upswing following the recapture of Constantinople in 1261, the empire continued to deteriorate.
The Hundred Years' War was a conflict between France and England, lasting 116 years from 1337 to 1453. It was fought primarily over claims by the English kings to the French throne and was punctuated by several brief and two lengthy periods of peace before it finally ended in the expulsion of the English from France, with the exception of the Calais Pale. Thus, the war was in fact a series of conflicts and is commonly divided into three or four phases: the Edwardian War (1337-1360), the Caroline War (1369-1389), the Lancastrian War (1415-1429), and the slow decline of English fortunes after the appearance of Joan of Arc, (1429-1453). Though primarily a dynastic conflict, the war gave impetus to ideas of both French and English nationality. Militarily, it saw the introduction of new weapons and tactics, which eroded the older system of feudal armies dominated by heavy cavalry. The first standing armies in Western Europe since the time of the Western Roman Empire were introduced for the war, thus changing the role of the peasantry. For all this, as well as for its long duration, it is often viewed as one of the most significant conflicts in the history of mediaeval warfare.
The troubled 14th century saw both the Avignon Papacy of 1305–1378, also called the Babylonian Captivity of the Papacy (a reference to the Babylonian Captivity of the Jews), and the so-called Western Schism that lasted from 1378–1418. The practice of granting papal indulgences, fairly commonplace since the 11th century, was reformulated and explicitly monetized in the 14th century.
Indulgences came to be an important source of revenue for the Church, revenue that filtered through parish churches to bishoprics and then to the pope himself. This was viewed by many as a corruption of the Church. In the early years of the 15th century, after a century of turmoil, ecclesiastical officials convened in Constance in 1417 to discuss a resolution to the Schism.
Traditionally, councils needed to be called by the Pope, and none of the contenders were willing to call a council and risk being unseated. The act of convening a council without papal approval was justified by the argument that the Church was represented by the whole population of the faithful. The council deposed the warring popes and elected Martin V. The turmoil of the Church, and the perception that it was a corrupted institution, sapped the legitimacy of the papacy within Europe and fostered greater loyalty to regional or national churches. Martin Luther published objections to the Church. Although his disenchantment had long been forming, the denunciation of the Church was precipitated by the arrival of preachers raising money to rebuild the Basilica of Saint Peter in Rome. Luther might have been silenced by the Church, but the death of the Holy Roman Emperor Maximilian I brought the imperial succession to the forefront of concern. Lutherans' split with the Church in 1517, and the subsequent division of Catholicism into Lutheranism, Calvinism, and Anabaptism put a definitive end to the unified Church built during the Middle Ages.