From eRepublik Official Wiki
This page contains elements/concepts/ideas which are NOT part of eRepublik features.
A Supreme Commander (SC) is usually the highest military position in an international alliances.
A Supreme Commander is responsible for the combined military effort of the alliance, giving orders to individual countries and coordinating efforts in wars and battles, where timing can be crucial.
Their "second in command" can be known as Deputy Supreme Commander (dSC) or Military Commander (MC).