The idea to create an organisation for preserve peace between nations was born after the first world war trauma. In 1919 the league of nation was create.
More informations about the league:
http://www.historylearningsite.co.uk/modern-world-history-1918-to-1980/league-of-nations/
http://www.bbc.co.uk/history/worldwars/wwone/league_nations_01.shtml
http://www.un.org/fr/aboutun/history/1941-1950.shtml
Who celebrate the day of peace close to you ? Check it !
http://en.unesco.org/aspnet/globalcitizens/act/actions/peace-actions-greece
And take a look on web peace tv !
http://www.peacetv.tv/