What is the irony in beware of the dog?

The irony in the short story "Beware of the Dog" by Roald Dahl lies in the fact that the main character, a Royal Air Force pilot named Peter Williamson, is unaware that he is actually the one being deceived. Despite his injuries and the care he receives from the hospital staff, he remains oblivious to the true intentions of those around him. The twist at the end reveals that he is not in an Allied hospital, but in an enemy hospital, being interrogated by the enemy. This dramatic irony adds depth to the story and highlights the theme of deception in wartime.