ἐπείσιον
From LSJ
μέγα γὰρ τὸ τῆς θαλάσσης κράτος → great is the power of the country that controls the sea, control of the sea is a great thing, the dominion of the sea is a great matter, the rule of the sea is a great matter, the rule of the sea is indeed a great matter, control of the sea is a paramount advantage