The Blue Mountains and Other Fairy Tales by Andrew Lang

There were once a Scotsman and an Englishman and an Irishman serving in the army together, who took it into their heads to run away on the first opportunity they could get. The chance came and they took it. They went on travelling for two days through a great forest, without food or drink, and without coming across a single house, and every night they had to climb up into the trees through fear of the wild beasts that were in the wood. On the second morning the Scotsman saw from the top of his tree a great castle far away...