Two Dutch migrants to Münster ​ — Jan Mathys , a baker from Haarlem , and Jan Beuckelson , known as John of Leiden — ​ were to play a decisive role in developments there .
Two Dutch migrants to Munster ​ — Jan Mathys , a baker from Haarlem , and Jan Beuckelson , known as John of Leiden — ​ were to play a decisive role in developments there .