Who began a new approach to international relations by using diplomacy?

Diplomatic history deals with the history of international relations between states. Diplomatic history can be different from international relations in that the former can concern itself with the foreign policy of one state while the latter deals with relations between two or more states. Diplomatic history tends to be more concerned with the history of diplomacy, but international relations concern more with current events and creating a model intended to shed explanatory light on international politics.[1]

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