On September 28, 1525, Martin Luther arranged for thirteen nuns to escape from their cloister in Freiberg, Germany. Luther's treatise is important on four accounts: First, Luther wanted to show his own humanist education. Martin Luther died on February 18th, 1546. In autumn 1525, Luther wrote The Bondage of the Will as a response to humanist and theologian Erasmus of Rotterdam's On Free Will.

He was 41 years old at the time of the wedding and she was just 26.
His teachings had won both popular and princely support in the Holy Roman Empire and beyond: by the time of his death, many principalities and cities in northern and eastern Germany had turned Lutheran and reforms had been implemented beyond the Empire’s borders in Denmark and Sweden. Luther eventually came to the conclusion that "his marriage would please his father, rile the pope, cause the angels to laugh, and the devils to weep." Martin Luther married Katharina von Bora on June 13, 1525.

Source: Martin Luther, Against the Robbing and Murdering Hordes of Peasants, May 1525 "If God permits the peasants to extirpate the princes to fulfil his wrath, he will give them hell fire for it as a reward." Hans Luther, Martin's father, hoped to help his son by sending him to law school so he could later be a lawyer and have a secure future.

Source: Letter of Martin Luther to John Ruhel, 4 May 1525

This is most likely the reason Luther's father chose this university for his son. The University of Erfurt, founded in 1392 was one of the best German universities at this time.
Martin Luther married Katharina on 13 June 1525, before witnesses including Justus Jonas, Johannes Bugenhagen, and Barbara and Lucas Cranach the Elder.