The Last Pagans of Europe
By the 12th century, Christianity had become the dominant religion across most of Europe. Yet, a stubborn pocket of paganism remained along the southern and eastern shores of the Baltic Sea. Peoples like the Old Prussians, Livonians, Estonians, and, most notably, the Lithuanians, continued to worship their ancestral gods of nature, thunder, and the underworld. To the Christian kingdoms of Europe and the ever-powerful Papacy, this was an unacceptable anomaly—a frontier of faithlessness that needed to be brought into the fold.
And so, beginning in the late 12th century, a series of Papal bulls authorized holy war against these northern pagans. Unlike the crusades to the Middle East, which were about recapturing holy sites, the Northern Crusades had a different objective: the complete subjugation and conversion of entire peoples. The choice offered was often stark and simple: baptism or death.
The Men in White Mantles: Enter the Teutonic Knights
While Danish and Swedish kings, along with other German nobles, played a part, the story of the Baltic Crusades is dominated by one group: the Order of Brothers of the German House of Saint Mary in Jerusalem, better known as the Teutonic Knights.
Originally founded in the Holy Land, the Teutonic Order found its purpose dwindling as Crusader fortunes waned in the Middle East. In 1226, a Polish duke, Konrad of Masovia, made a fateful invitation. Plagued by raids from the neighboring pagan Old Prussians, he asked the Teutonic Knights to help secure his border. The Knights, led by the shrewd Grand Master Hermann von Salza, saw an unparalleled opportunity. They secured a papal bull granting them ownership of any land they conquered from the pagans, effectively giving them a blank check to build their own state.
They arrived not just as missionaries but as an unstoppable military and administrative machine. Merging with another local order, the Livonian Brothers of the Sword, they became the dominant power in the region. Clad in their iconic white mantles adorned with a black cross, the Teutonic Knights were disciplined, well-equipped, and utterly ruthless.
Conquest by Sword and Stone
The Knights’ method of conquest was systematic and brutal. Their campaigns, or reise, were annual affairs where knights from across Europe would travel to the Baltic to “fight for Christ” (and gain honor and spoils). These weren’t pitched battles as much as devastating raids designed to terrorize the local population, burn villages, and destroy sacred groves.
Where they conquered, they built. The Knights erected a stunning network of imposing brick fortresses known as Ordensburgen. These castles, many of which still stand today, were marvels of Gothic architecture and military engineering. The grandest of all, Malbork Castle (Marienburg) in modern-day Poland, became the Order’s headquarters and the largest brick castle in the world. These fortresses were not just defensive structures; they were bases for further conquest, centers of administration, and powerful symbols of the new German-speaking, Christian authority.
To consolidate their rule, the Knights encouraged mass German immigration, a process known as the Ostsiedlung. German peasants, merchants, and artisans settled the newly conquered lands, founding towns and farming the fields, often displacing or subjugating the native Prussian, Livonian, and Estonian populations. Over decades, the native languages and cultures were systematically suppressed and, in the case of the Old Prussians, eventually extinguished entirely.
When the Enemy Converts
For over a century, the Knights’ primary justification for their state-building project was the war against the pagans. Their most formidable opponent was the Grand Duchy of Lithuania, a powerful state that had resisted both conversion and conquest.
Then, in 1386, the strategic landscape shifted dramatically. The Lithuanian Grand Duke Jogaila agreed to convert to Christianity to marry the young Queen Jadwiga of Poland. This act created the powerful Polish-Lithuanian Union, uniting the Knights’ two biggest adversaries. More importantly, it eliminated the Knights’ entire reason for being. How could they wage a holy war against a Christian king and a Christian nation?
The Knights’ answer was simple: they didn’t stop. They shamelessly continued their attacks, claiming the Lithuanian conversion was a sham. This blatant hypocrisy exposed what many already suspected: the “crusade” was now purely a war for land and political power. The Papacy and the rest of Europe grew increasingly skeptical of the Order’s motives.
The Tide Turns: The Battle of Grunwald
The simmering conflict between the Teutonic Order and the Polish-Lithuanian Union finally boiled over into open war. On July 15, 1410, the two sides met in one of the largest battles of medieval Europe: the Battle of Grunwald (also known as the Battle of Tannenberg).
A massive Polish-Lithuanian army, bolstered by Tatar and Bohemian mercenaries, faced the elite, heavily-armored force of the Teutonic Knights. In a brutal, day-long struggle, the Order’s army was annihilated. Grand Master Ulrich von Jungingen was killed along with the majority of his senior command. It was a catastrophic defeat that shattered the myth of Teutonic invincibility.
While the Order survived Grunwald, it never recovered. The defeat marked the beginning of its decline, leading to further wars with Poland and its eventual transformation into a vassal state under the Polish crown.
A Legacy Etched in Brick and Blood
The Baltic Crusades officially ended in the 15th century, but their legacy is deep and complex. They succeeded in their primary goal: organized paganism vanished from Europe. They redrew the political, ethnic, and religious map of Northeastern Europe, creating the foundations of modern-day states like Latvia and Estonia, while eliminating others, like Prussia.
Today, the legacy is viewed through starkly different lenses. For Poland and Lithuania, the Knights are national villains, a symbol of aggressive foreign invasion. For Estonians and Latvians, they represent centuries of German domination. In Germany, the Order was sometimes romanticized by nationalists as pioneers of German civilization in the East. What remains for all are the magnificent brick castles, silent witnesses to a violent, transformative era when the cross and the sword marched together to forge a new Europe in the fires of a forgotten holy war.