The European Split was caused by the inefficient government starting by Dean Thomas than with Seamus Finnegan. Finnegan did nothing to change the rules of Thomas about having the Europeans and the Americans submissive to the Ministries rules, so the European and the American wizards left, with no war or battle since the Ministry was busy with Voldemort at the time.
The countries that were part of the American Split included the United States, Canada, Mexico, Brazil, Chile, Argentina, Cuba, Haiti, Peru, Ecuador, Columbia, Bolivia, and Venezuela, Britian, France, Spain and Portugaul. After the Split, each country created its own magical governing body, like the American Wizarding Confederation (AWC, USA) and the European Confederation of Wizards (CWC, Canada)
People involved in the European Split incuded: Albus Dumbledore, Ferdinand Epans & his son Victor Epans, Mavis Gwen, and Jose Menica.