This month, we mark the 504th anniversary of the Leipzig Disputation, an academic debate held at the University of Leipzig between Andreas Bodenstein von Karlstadt of the University of Wittenberg (the challenger) and Johann Eck of the University of Ingolstadt. Martin Luther also participated, as his statements were at the center of the dispute. The event is remembered as a key moment in Reformation history, as it was the first time Luther publicly acknowledged that both popes and church councils had made errors. (Philip Bartelt has written an excellent primer on the Leipzig Disputation that can be found here.)
However, that is not the only reason the Leipzig Disputation was significant. It also had implications for the relationship between Karlstadt and Luther. Years later, both men would point to this occasion as a moment when things went sour. The story of their relationship is as fascinating as the debate itself.
The University of Wittenberg was founded in 1502 according to the special wish of its elector, Frederick III. As it was not an ecclesiastical foundation, Frederick had to provide much of the university’s early funding from his own purse, building an institution completely from scratch.  It was therefore a matter of great personal pride for the elector, who was eager to attract talent.
Among his early acquisitions was a bright young student named Andreas Bodenstein von Karlstadt, who quickly ascended the university ranks: master’s degree in 1505, first major work in 1507, doctorate in 1510, archdeacon and chair of the theology department in the same year, then university chancellor in 1511, at which point he was still only twenty-five years old. Karlstadt was the greatest theological mind the university had in its first decade.
Then, in 1512, Karlstadt awarded a doctorate to Martin Luther, a man three years his senior but behind him in terms of academic achievement. The next five years brought a major shift in the theology department’s activity. Luther’s lectures on the Bible had a sizable impact, and Karlstadt was forced to reconsider some of his views. Lyndal Roper, a biographer of Luther who gives particular focus to his relationship with Karlstadt, has written, “Both radical and passionate, Karlstadt easily got lost in the thread of his own thought and needed direction: Luther’s intensity seems to have unleashed his creativity, sparking him to rethink all his intellectual and spiritual positions.” 
By the time Luther published his Ninety-Five Theses, both men were rapidly moving in the direction of reform. They each made important contributions, but Luther seems to have been the better communicator. (Even in reading their works today, I can confirm that Karlstadt’s do not possess the same clarity and dynamism.) Roper writes that, “Between 1517 and 1521…Luther’s reputation eclipsed Karlstadt’s almost completely,”  even as Karlstadt was moving beyond Luther in his push for reforms.
It was in the lead-up to the Leipzig Disputation of 1519 that this shift in the university power dynamic began to take a more significant toll. Karlstadt was eager to defend the Wittenberg theological method in print and in person, but despite his creative efforts, which included innovations in the use of print media, all anyone wanted to talk about was Luther: a man whose academic credentials were still, at that point, inferior to Karlstadt’s. Roper notes the following.
“Although Karlstadt had been [Johann] Eck’s original target, the final theses for debate scarcely hid the fact that Luther was the real antagonist. During the negotiations about where and how the debate was to be held, Luther corresponded directly with Eck, making no bones about the fact that he and Eck were the ones who counted. Moreover, all observers agreed that Karlstadt had the worst of the debate.” 
Indeed, Karlstadt was an unimpressive debater in comparison with Eck. Despite extensive preparations, Karlstadt struggled through the many long days of disputation over the issue of free will, when in fact nearly everyone was there to see if Luther would be given permission to enter the lists. When approval was finally granted, Luther and Eck engaged in a more fiery debate about the nature of papal power, and although Luther was judged by most observers to be the loser, he won a great deal of public support for his ideas. In contrast, Karlstadt looked weak, his star rather diminished.
It was meant to be Karlstadt’s moment to shine, but all anyone remembered was Luther.
The Black Bear
Over the next few years, the friendship and working relationship between Luther and Karlstadt disintegrated into an angry war of words. Karlstadt moved in a more radical theological direction: he denied the Real Presence in the Lord’s Supper, promoted the destruction of Wittenberg’s images, and eventually rejected the baptism of infants. Luther particularly objected to changes Karlstadt made at the Wittenberg parish church during the former’s absence in 1522. Karlstadt also had a negative history with the elector, whom he had angered on multiple occasions. Soon after Luther’s return to Wittenberg, Karlstadt departed to pastor the congregation of Orlamünde, where he had free reign to implement his new ideas about the sacraments and promote a mystical understanding of human existence.
When Luther entered the region of Thuringia in 1524 on a preaching tour, Karlstadt requested a meeting at the Black Bear Inn in Jena. There the two men aired their grievances, with one of Karlstadt’s allies producing a transcript that was soon released to the public. (The accuracy of this transcript is certainly debatable, though it likely reflects the general subject matter and tenor of the conversation.) One of their points of dispute was what had happened at Leipzig. Here is their purported exchange.
Luther: “I did reprove you at Leipzig because you were so proud and wanted to dispute before me. Finally I granted you the honor and allowed it to happen.”
Karlstadt: “Oh, Mr. Doctor, how can you say that? For you know that when I was already disputing you were still uncertain whether or not you would be allowed to dispute. For that, I appeal to Duke George’s councilors and the University of Leipzig. But you must always speak in such a way that you maintain your reputation and stir up hatred for other people.” 
The Reformation shattered not only institutions, but also human relationships. The break between Luther and Karlstadt foreshadowed the eventual fissure between the Lutheran and Reformed branches of the evangelical movement. The heat of battle at Leipzig helped to lead Martin Luther to some of his greatest Reformation breakthroughs, but it also marked the beginning of the end of what had been a profitable friendship: one destroyed not only by differing theological visions, but also clashing personalities.
 Grossman, Maria. Humanism in Wittenberg: 1485-1517 (Nieuwkoop: B. De Graaf, 1975), 40-1.
 Roper, Lyndal. Martin Luther: Renegade and Prophet (New York: Random House, 2016), 79.
 Roper, 208-9.
 Roper, 210.
 Sider, Ronald J., editor. Karlstadt’s Battle with Luther: Documents in a Liberal-Radical Debate (Philadelphia: Fortress Press, 1978), 46-7.