Mellencamp's Sons Victim's Pulverized Face

8/17/2013 12:15 AM PDT

John Mellencamp's Sons -- Victim's Pulverized Face [PHOTOS]

This is what John Mellencamp's two teenage sons allegedly did to a 19-year-old Indiana college student last month.

As we reported, the boys -- 18-year-old Speck and 19-year-old Hud -- have been charged with felony battery in connection with the July 29th attack, along with a 3rd alleged attacker, Ty Smith, the son of the baseball coach at Indiana U.

Cops say the victim suffered facial fractures and cuts that required stitches, and as you can see from the pics, the attack was gruesome.

The fight was all about retaliation -- we're told Speck was beaten up earlier that night at a house party, and hours later returned for revenge.  The victim was not involved in the previous fight ... he was just at the wrong place at the wrong time.

Two of the alleged attackers have turned themselves in and are out on $5k bail.  The third is expected to turn himself in sometime Saturday.