If you'll make that '1815' it's Switzerland.
Switzerland
Switzerland has been neutral since 1515. Their neutrality was recognized and granted by Europe in 1815 after the Napoleonic Wars. They've been neutral longer than most other European countries.
Switzerland has not been at war with another nation since 1815. Until 1515, Switzerland led an expansionist policy noted by many successful invasions of foreign nations. In 1515 Switzerland was defeated at the Battle of Marignano by the French army. This ended Switzerland's expansionist policy and began neutrality.
Latin Americas
Are you talking about the state or the country
Ireland is a neutral country, so it has not been officially involved in any wars.
Manchester grammer it has been there from 1515-2008 and is still there now
None. Australia has never been invaded by a foreign country.
Sweden has been at peace the longest as it has not been involved in a war since 1814.
Japan
If the president was an American citizen for more that 14 years, then maybe.
Because the country is still linked to Russia's weak economy. :)