The Convent of Wesel was long believed to be a clandestine assembly of Protestant leaders in 1568 that helped establish foundations for Reformed churches in the Dutch Republic and northwest Germany. However, Jesse Spohnholz shows that that event did not happen, but was an idea created and perpetuated by historians and record keepers since the 1600s. Appropriately, this book offers not just a fascinating snapshot of Reformation history but a reflection on the nature of historical inquiry itself. The Convent of Wesel begins with a detailed microhistory that unravels the mystery and then traces knowledge about the document at the centre of the mystery over four and a half centuries, through historical writing, archiving and centenary commemorations. Spohnholz reveals how historians can inadvertently align themselves with protagonists in the debates they study and thus replicate errors that conceal the dynamic complexity of the past.