What conflict brought the countries of Chile and Argentina to the brink of War, where the first planned military invasion was halted without incident?
Operation Soberanía:  The invasion was halted after a few hours and Argentine forces retreated from the conflict zone without a fight. Beagle conflict: The Beagle conflict was a border dispute between Chile and Argentina over the possession of Picton, Lennox and Nueva islands and the scope of the maritime jurisdiction associated with those islands that brought the countries to the brink of war in 1978.
The Beagle conflict was a border dispute between Chile and Argentina