Here he was in the middle of an adventure with grown-up soldiers.

He threw out his chest and tried to look manly.
The captain sat down in a chair at the end of a long table, drew a black book to him--a black book covered with dust--and began to rub a rusty pen-nib on his sword, which was not rusty.
'Come now,' he said, opening the book, 'tell me how you came here.

And mind you speak the truth.' 'I _always_ speak the truth,' said Philip proudly.
All the soldiers rose and saluted him with looks of deep surprise and respect.
'Well, nearly always,' said Philip, hot to the ears, and the soldiers clattered stiffly down again on to the benches, laughing once more.
Philip had imagined there to be more discipline in the army.
'How did you come here ?' said the captain.
'Up the great bridge staircase,' said Philip.
The captain wrote busily in the book.
'What did you come for ?' 'I didn't know what else to do.

There was nothing but illimitable prairie--and so I came up.' 'You are a very bold boy,' said the captain.
'Thank you,' said Philip.

'I do _want_ to be.' 'What was your purpose in coming ?' 'I didn't do it on purpose--I just happened to come.' The captain wrote that down too.