War and Refugees in the Medieval and Early Modern Periods: History of War Refugees Series (3)

Throughout the Medieval and Early Modern periods, war remained a principal driver of mass displacement. Spanning from roughly the 5th to the 18th centuries, these eras were marked by profound transformations in political, religious, and economic structures. The collapse of empires, the rise of kingdoms and nation-states, religious crusades, dynastic conflicts, and sweeping conquests all produced vast refugee movements. While often overshadowed by more contemporary refugee crises, the forced migrations of these centuries shaped global demographics, cultural identities, and interreligious dynamics that reverberate even today.

The Early Islamic Conquests and Byzantine-Persian Wars

The early Islamic conquests (7th–8th centuries CE) catalyzed major demographic shifts across the Middle East, North Africa, and parts of Europe. As Arab-Muslim forces rapidly expanded, many local populations fled or were displaced, particularly from contested border zones. While some communities, such as the Christian and Jewish populations under Islamic rule, were integrated and granted dhimmi status, others resisted and were expelled or relocated.

Prior to the Islamic conquests, the protracted wars between the Byzantine and Sassanian Persian Empires (6th–7th centuries) had already weakened these regions and created instability. The Byzantine–Sassanid War of 602–628 CE devastated large swaths of the Near East, including cities such as Antioch and Jerusalem. Refugee flows from these prolonged conflicts often ended up in border cities or the interiors of the respective empires, placing stress on urban centers and rural economies alike (Greatrex and Lieu, 2002).

The Viking Raids and Migrations

Between the 8th and 11th centuries, Viking incursions into the British Isles, Francia, and beyond created massive displacements. The Norse raiders, originally seasonal pillagers, gradually transitioned into settlers, establishing territories in northern France (Normandy), Ireland, and eastern England (Danelaw). These invasions devastated monastic communities and urban centers.

Many Anglo-Saxon and Celtic populations fled inland or to safer regions under threat of enslavement, death, or assimilation. The refugee movements during this period were often undocumented but have been inferred through archaeological evidence and fragmented historical accounts, such as those in the Anglo-Saxon Chronicle. The trauma of these invasions etched itself into cultural memory, with chroniclers lamenting entire regions left desolate.

The Crusades: Holy War and Human Displacement

The Crusades (1095–1291) were among the most significant transcontinental military campaigns of the medieval era. Initiated by Pope Urban II to reclaim the Holy Land, the Crusades ultimately led to centuries of conflict between Christian and Muslim powers, and often with collateral damage to Jewish communities caught in between.

In the Levant, both Muslim and Christian populations were displaced repeatedly. The sack of Jerusalem in 1099 by Crusaders resulted in the mass slaughter of Muslim and Jewish residents and forced survivors to flee or convert. Over time, cities like Acre and Antioch experienced cyclical waves of conquest, siege, and resettlement (Tyerman, 2006). Many refugees sought safety in neighboring Islamic empires like the Abbasid Caliphate or Seljuk Sultanate.

Back in Europe, the People's Crusade and later Crusader zealotry often turned against local Jewish populations. Pogroms in cities like Worms, Mainz, and Cologne saw Jewish families massacred or expelled, triggering internal displacement and migrations eastward into Poland and Lithuania, where tolerance was comparatively greater (Chazan, 1987).

Mongol Invasions: A Continent in Flight

The Mongol invasions of the 13th and 14th centuries reshaped the demographics of Eurasia. Led by Genghis Khan and his successors, the Mongol Empire expanded from China to Hungary, destroying cities, depopulating regions, and instilling widespread terror.

In Central Asia, entire urban populations were displaced. Cities like Nishapur, Herat, and Baghdad faced catastrophic destruction. The Mongols’ sack of Baghdad in 1258, one of the deadliest events in medieval history, resulted in the deaths of hundreds of thousands and a flood of refugees across Mesopotamia and into Syria and Anatolia (Morgan, 1986).

In Eastern Europe, the invasion of Kievan Rus’ and Poland by Mongol forces forced Slavic populations into forests and mountains or toward the west. The Hungarian Kingdom received tens of thousands of refugees fleeing the Mongol advance in the 1240s, and King Béla IV issued decrees to accommodate and protect them (Jackson, 2005).

The Black Death and War-Induced Panic

Although primarily a pandemic, the Black Death (1347–1351) intersected with ongoing wars to exacerbate displacement. Widespread panic over disease and the belief that enemies were poisoning wells or spreading the plague led to expulsions and mob violence. Jewish communities were scapegoated and expelled from cities like Strasbourg, Speyer, and Basel, producing a new wave of religious refugees during a time of already heightened instability.

This pattern overlapped with the ongoing Hundred Years’ War (1337–1453) between England and France. The war devastated rural France, prompting widespread depopulation and internal displacement. Civilians fled from advancing armies, marauding mercenaries, and scorched-earth campaigns, often relocating to walled cities or safer feudal territories. By the war’s end, entire regions like Normandy and Aquitaine had undergone demographic collapse and reconstitution (Allmand, 1988).

The Spanish Reconquista and Inquisition

One of the most impactful instances of religious war-induced displacement in medieval Europe was the Spanish Reconquista and subsequent Inquisition. As Christian kingdoms retook the Iberian Peninsula from Muslim control, Muslim and Jewish populations found themselves increasingly persecuted.

Following the fall of Granada in 1492, the last Muslim stronghold in Spain, the Catholic Monarchs issued the Alhambra Decree, expelling all Jews who refused conversion. An estimated 200,000 Jews were forced to flee, many seeking refuge in the Ottoman Empire, North Africa, and Italy (Roth, 2002). Similarly, Muslims were subjected to forced conversion, and later, expulsion under Philip III in 1609–1614, resulting in the flight of approximately 275,000 Moriscos (converted Muslims) (Harvey, 2005).

The forced migration of these groups not only caused immense suffering but also shaped the character of receiving regions. The Sephardic diaspora enriched the cultural and economic life of the Ottoman Empire, while Moriscos faced mixed reception across North Africa due to religious and cultural differences that had developed during centuries of Iberian isolation.

The Reformation and Wars of Religion

The Protestant Reformation, beginning in 1517, set off a cascade of religious wars across Europe, from the German Peasants’ War (1524–1525) to the French Wars of Religion (1562–1598) and the English Civil War (1642–1651). Religious dissenters frequently found themselves exiled, banished, or forced into clandestine existence.

The Edict of Nantes (1598) temporarily granted French Protestants (Huguenots) religious freedoms, but its revocation in 1685 by Louis XIV led to the flight of over 200,000 Huguenots to Protestant regions such as the Netherlands, England, and Prussia (Scoville, 1960). These refugees carried with them significant cultural and commercial skills, contributing to their host countries' economies but leaving behind a devastated and homogenized French religious landscape.

The Thirty Years’ War

The Thirty Years’ War (1618–1648) was one of the most devastating and transformative conflicts in European history. Fought largely within the fragmented Holy Roman Empire, the war had religious, dynastic, and political dimensions. The conflict’s brutality — involving foreign mercenaries, sieges, famine, and disease — decimated civilian populations.

Estimates suggest that up to 8 million people died during the war, and between 15–30% of the German population was displaced or perished (Parker, 1984). Entire villages were abandoned, and regions such as Bohemia, Brandenburg, and the Palatinate witnessed refugee flows across borders into the Netherlands, Switzerland, and Scandinavia.

One under-recognized aspect was the movement of women and children, many of whom fled with no male guardians or ended up in refugee encampments or servitude. The war set a precedent for future refugee crises in terms of scale and complexity.

The English Civil War and Irish Conflicts

In the British Isles, the English Civil War (1642–1651) and related conflicts in Ireland and Scotland displaced tens of thousands. Royalist and Parliamentarian forces ravaged the countryside, and political or religious opponents often fled into exile. The Irish Rebellion of 1641 and subsequent Cromwellian conquest resulted in massacres and forced deportations of Irish Catholics. Thousands were sent as indentured servants to the Caribbean, especially Barbados and Saint Kitts (Canny, 2001).

These early modern forced migrations were precursors to the colonial patterns of displacement seen in the 18th and 19th centuries, blending political, economic, and religious motivations for exile.

Conclusion

The Medieval and Early Modern periods were marked by a recurring cycle of war and forced migration. From religious persecution to dynastic conflicts and imperial ambitions, war upended the lives of millions, scattering them across continents. While exact numbers often elude historians due to the fragmentary nature of medieval records, the human cost of these displacements is unmistakable.

Understanding this historical context is essential not only for appreciating the deep roots of the modern refugee experience but also for drawing lessons on tolerance, inclusion, and the devastating consequences of unbridled militarism and ideological extremism. These eras remind us that refugees are not a modern invention but a constant in human history, shaped by the same fears, hopes, and struggles that persist today.

Bibliography

Allmand, Christopher. The Hundred Years War: England and France at War c.1300–c.1450. Cambridge University Press, 1988.

Canny, Nicholas. Making Ireland British, 1580–1650. Oxford University Press, 2001.

Chazan, Robert. European Jewry and the First Crusade. University of California Press, 1987.

Greatrex, Geoffrey, and Samuel N. C. Lieu. The Roman Eastern Frontier and the Persian Wars (Part II, AD 363–630). Routledge, 2002.

Harvey, Leonard Patrick. Muslims in Spain, 1500 to 1614. University of Chicago Press, 2005.

Jackson, Peter. The Mongols and the West: 1221–1410. Pearson Education, 2005.

Morgan, David. The Mongols. Blackwell Publishing, 1986.

Parker, Geoffrey. The Thirty Years' War. Routledge, 1984.

Roth, Norman. Conversos, Inquisition, and the Expulsion of the Jews from Spain. University of Wisconsin Press, 2002.

Scoville, Warren C. The Persecution of Huguenots and French Economic Development, 1680–1720. University of California Press, 1960.

Tyerman, Christopher. God's War: A New History of the Crusades. Harvard University Press, 2006.