six o'clock
`` That 's certainly a hard luck story , '' he said ; `` but , '' he added cheerfully , `` it 's nothing to the hard luck you 'll strike when you ca n't tell why you left the army . '' Hamlin turned with an exclamation , but Billy held up his hand . `` Now wait , '' he begged , `` we have n't time to get mussy . At six o'clock your leave is up , and the troop train starts back to camp , and -- '' Mr. Hamlin interrupted sharply . `` And the _ Adriaticus _ starts at five . '' Billy did not heed him . `` You 've got two hours to change your mind , '' he said .