On the other side of the lake stood a fine, illuminated castle from which came the merry music of horns and trumpets. There they all landed, and went into the castle,
and each prince danced with his princess; and the soldier, who was still invisible, danced with them too. When any of the princesses had a cup of wine set by her, he drank it all up, so that when she put the cup to her mouth it was empty. At this, too, the youngest sister was terribly frightened, but the eldest always silenced her.
They danced on till three o'clock in the morning, and then all their shoes were worn out, so that they were obliged to leave. The princes rowed them back again over the lake (but this time the soldier placed himself in the boat with the eldest princess); and on the opposite shore they took leave of each other, the princesses promising to come again the next night.
When they came to the stairs, the soldier ran on before the princesses, and laid himself down. And as the twelve, tired sisters slowly came up, they heard him snoring in his bed and they said, 'Now all is quite safe'. Then they undressed themselves, put away their fine clothes, pulled off their shoes, and went to bed.
In the morning the soldier said nothing about what had happened, but determined to see more of this strange adventure, and went again on the second and third nights. Everything happened just as before: the princesses danced till their shoes were worn to pieces, and then returned home. On the third night the soldier carried away one of the golden cups as a token of where he had been.
As soon as the time came when he was to declare the secret, he was taken before the king with the three branches and the golden cup; and the twelve princesses stood listening behind the door to hear what he would say.
The king asked him. 'Where do my twelve daughters dance at night?'
The soldier answered, 'With twelve princes in a castle underground.' And then he told the king all that had happened, and showed him the three branches and the golden cup which he had brought with him.
The king called for the princesses, and asked them whether what the soldier said was true and when they saw that they were discovered, and that it was of no use to deny what had happened, they confessed it all.
So the king asked the soldier which of the princesses he would choose for his wife; and he answered, 'I am not very young, so I will have the eldest.' -- and they were married that very day, and the soldier was chosen to be the king's heir.