Usage patterns
〈人〉を特使に任命するto appoint someone as a special envoy
The prime minister appointed the former minister as a special envoy.
特使を派遣するto dispatch a special envoy
The government dispatched a special envoy for the peace negotiations.
特使として〈場所〉を訪問するto visit a place as a special envoy
He visited North Korea as a special envoy.