Katherine Luther, a former nun, was a decisive, assertive partner of Martin Luther, unlike most preacher's wives of her time.

When Martin Luther posted his "theses" on the door of the Wittenberg church in 1517, protesting corrupt practices, he was virtually unknown. Within months, his ideas spread across Germany, then all of Europe; within years, their author was not just famous, but infamous, responsible for catalyzing the violent wave of religious reform that would come to be known as the Protestant Reformation and engulfing Europe in decades of bloody war. Luther came...