At least, it's not a cave now, for it's filled up.

But it was there the trooper, under cover of night, led the colonel and the captain.

They didn't do more than mark the place then, for fear an alarm might be given by a sentinel within.
"`Now,' says Colonel Frank, `the castle's ours; and not a soul inside it shall be there by this time to-morrow.' "`What shall you do ?' says Captain Morgan, pale, and with a shaky voice.
"`Do?
Art thou a dunce, Morgan?
Without doubt, at the end of that cave is a way up into the castle; and though the passage be too narrow for all my troop, three men and a captain will suffice to lay faggots and light them at the door.

What say you, comrade ?' "`What!' cries Morgan, `would you burn the place?
No, no, colonel; we will capture it if we can, but it is no soldier's work to burn men in their beds!' "`Fool!' exclaims the colonel, in a passion, `it is no captain's work to read sermons to his colonel, sirrah! These rebels shall be smoked out like all other vermin!' "`But,' says the captain once more, and very pale--`but I hear there is a lady in the castle, and--' "`Peace, sir, on your peril!' exclaims the colonel, `and hold yourself ready to obey orders when I shall give them.' It was no use saying more, young Morgan saw that.

As it was, he knew his colonel half suspected him of some treachery, and for the rest of that day put a watch upon him.