Answer:
Joby is crying preparing for the battle. He is so scared to find out what will happen when the time comes.
And in order to comfort him, the general said "God's truth. Thinking of everything ahead, both sides figuring the other side will just give up, and soon, and the war done in weeks, and us all home. Well, that's not how it's going to be. And maybe that's why I cried."
The general regularly motivates and encourages Joby and he makes him realize he is an essential piece to the army.