He who controls the sea controls everything.

Originally quoted by Cicero in Letters to Atticus (10, 8, 4.): ... cuius omne consilium Themistocleum est. existimat enim qui mare teneat eum necesse esse rerum potiri. | Translation: "On the contrary, his view is entirely that of Themistocles: for he holds that the master of the sea must inevitably be master of the empire."