My grandfather was in the artillery in France and his brother was in Salonika - I never knew either of them, but I did know an old boy over here who joined up at 14, lied about his age - they told him his teeth were too bad the first time he tried, possibly they suspected the truth, but he went and had them all out and returned a few days later and was accepted - he wouldn't talk about anything that happened after that until he got back afterwards...
Always worth reading All Quiet on the Western Front or Goodbye To All That...