The term Pax Austriaca, sometimes Pax Habsburgica, has been used by scholars to describe the imperial ideology of the House of Habsburg, also known as House of Austria. The Archduke Frederick III is credited as the initiator of the ideology as he was the first Habsburg to be elected Holy Roman Emperor, and coined the motto A.E.I.O.U. (All the world is subject to Austria). His successor Emperor Maximilian I expanded Habsburg territories and did so with marriages rather than war, thus establishing the motto "Bella gerunt alii, tu felix Austria nube" ("let others wage war; you, happy Austria, marry"). Charles V notably attempted to actually enforce the hegemonical peace in Europe. Further attempts to establish a Pax Habsburgica in Europe continued until the 30 years war. The Peace of Westphal