Editors. "Gregory XIV excommunicates Henry IV of France". The Literary Encyclopedia. First published 01 February 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=15422, accessed 09 March 2014.]
Pope Gregory XIV issues a monitorial, excommunicating Henry IV of France for his allegiance to the Huguenot faith. The Pope thus allies himself with the Catholic League, headed by the Duke of Mayenne and supported by Philip II of Spain, that aims to do all it can to prevent Henry IV's accession to the throne.