Editing Antipope John XXIII (section)

=== Flight from the Council of Constance ===
In March, John escaped from Constance disguised as a postman.<ref name=Miranda/> According to the Klingenberger Chronicle, written by a noble client of [[Frederick IV, Duke of Austria]], John XXIII traveled down the Rhine to [[Schaffhausen]] in a boat, while Frederick accompanied him with a small band of men on horseback. There was a huge outcry in Constance when it was discovered that John had fled, and Sigismund was furious about this setback to his plans for ending the Schism. The King of the Romans issued orders to all the powers on the Upper Rhine and in Swabia stating that he had declared Frederick to be an outlaw and that his lands and possessions were forfeit. In due course this led to a great deal of political upheaval and many Austrian losses in the region, notably in [[Aargau]] to the [[Swiss Confederation]].

In the meantime, Antipope John XXIII and Frederick fled further downriver along the Rhine to the town of [[Freiburg im Breisgau]], which recognised the duke of Austria as its lord. There Sigismund's lieutenant [[Ludwig III, Elector Palatine]] caught up with them. He convinced Frederick that he stood to lose too much by harbouring the fugitive pope, and the Austrian duke agreed to give himself and John up and return to Constance.<ref>Brandmüller, Walter. ''Das Konzil von Konstanz'', 1414–1418 (Paderborn, 1991){{ISBN?}}</ref>