Who commands the sea?

From ‘Raiders, submarines and some naval problems’, The Spectator,
20 January 1917: At the moment the enemy’s fleet is compelled to remain in its own ports and to challenge us from safe retreats, sometimes behind lock-gates and always behind well-sown minefields. Still, the fact remains that the enemy can come out if they like, though we cannot make them do so when we like, and further that with good luck they can actually smuggle out a raider or two. We are top-dog, but up till now we have not been able to get a good bite at the under-dog, and he remains, though in a humiliating position, quite fit for work and mischief.