Final answer:
The first multiple interstate diplomatic conference in world history was the Congress of Vienna in 1814-1815.
Step-by-step explanation:
The first multiple interstate diplomatic conference in world history was the Congress of Vienna in 1814-1815. It was held after the defeat of Napoleon Bonaparte and aimed to restore stability and order in Europe. The Congress of Vienna brought together representatives from various European countries to negotiate territorial changes and establish a balance of power.
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