In terms of marriage prospects, Martin Luther wasn’t necessarily a natural pick. The middle-aged theology professor was known to be loud, argumentative, and judgmental. He was always on the road, came from a common family, and didn’t have enough money to buy a wedding ring.

Oh, and the pope himself had compared the German theologian to a wild boar, declared him a heretic, and ordered all of his writings burned.

But a noblewoman and former nun named Katharina von Bora saw something in the 42-year-old preacher that captivated her. When the couple married in 1525, it was a scandal that reverberated across Europe—and the beginning of a partnership that lasted more than two decades and shaped the course of history. (Read