When George. Ill, was on board a yacht, the Captain reported, "Please your Majesty, it is twelve o'clock;" but fearing that this might be deemed too pretumptous an assertion, even prefaced as it was, and to remind him of his royal prerogative, to "make it so." humbly added, "but not unless your Majesty pleases." (Army and Navy Chronicle, October 26, 1837)
It's a time-honored naval phrase.
The captain is found at leisure. "Twelve o'clock, sir," the messenger exclaims, and indicates briefly the latitude of the vessel, and the ship's course and speed. On the captain signifying that he is satisfied and replying, "Thank you, make it so!': the sentry strikes eight bells, the boatswain's mate pipes for dinner, and in a moment the men are hard at work eating their dinners, for after such a morning's drill in fresh salt air who would not be a good trencherman? (How Our Navy is Run: A Description of Life in the King's Fleet, 1902)