I didn't know that I was so far

A big battle was going on during the First World War. Guns were firing, and shells and bullets were flying about everywhere. After an hour of this, one of the soldiers decidedthat the fighting was getting too dangerous for him, so he left the front line and began to go away from the battle. After he had walked for an hour, he saw an officer coming towards him. The officer stopped him and said, “ where are you going?”

　　“I'm trying to get as far away as possible from the battle that's going on behind us, sir,” the soldier answered.

　　“Do you know who I am?” the officer said to him angrily. “I'm your commanding officer.”

　　The soldier was very surprised when he heard this and said, “My God, I didn't know that I was so far back already!”