Thank you for the opportunity to help you with your question!
"Over there" is a patriotic song and created to motivate young men to join the army. This song was used in WWI and in some occasions during WWII also.
Like most motivating songs, this song uses repetition to make a point strong, like the opening line - "Johnny, get your gun, get your gun, get your gun. Take it on the run, on the run, on the run"
It uses various emotions from fear to proud to bring emotional turmoil inside the young man and get them inclined towards joining the army - "Hear them calling you and me, every son of liberty" and "tell your sweetheart not to pine, to be proud her boy's in line"
It also tries to paint an image of urgency to make decision making fast - "Hoist the flag and let her fly, Yankees doodle do or die"
Some people call it a propaganda song while other call it a patriotic song. Whatever the truth is, this song indeed served its purpose.
Content will be erased after question is completed.