The Beagle conflict is seen as the main reason for Chilean support to the United Kingdom during the Falklands War of 1982.
The conflict began in 1904 with the first official Argentine claims over the islands that have always been under Chilean control.:§164 The conflict passed through several phases: since 1881 Chilean islands, since 1904 disputed islands, direct negotiations, submitted to a binding international tribunal, direct negotiations again, brinkmanship and settlement.
The conflict was resolved through papal mediation and since 1984 Argentina recognizes the islands as Chilean territory. The 1984 treaty resolves also several collateral issues of great importance, including navigation rights, sovereignty over other islands in the Fuegian Archipelago, delimitation of the Straits of Magellan, and maritime boundaries south to Cape Horn and beyond.
See on en.wikipedia.org