Based on documents from the Historical Archive of the Ministry of Foreign Relations, - specifically reports exchanged between the respective missions and the Ministry of Foreign Affairs -, this text examines the substrate and the conduct of foreign policy of Chile to the Bolivarian Congress of the early twentieth century, specifically in the defense of its territory. Indeed, it is noted how Peru augments its territorial claims against Chile, through the promotion of compulsory arbitration, to force Chile into a revision of the treaties that had delivered territories after the Pacific War, or into a solution, contrary to Chile's interests, of those pending issues.