Yup, as per current rules... Independent characters ALWAYS fight as a separate unit in assaults.
Hence the power of the hidden power fist (...hence it's name too:)).
Dark Angels 1750 win/loss Record
Win - 23 (Belial helped wreck Ryan's puny Eldar)
Loss - 13 (Brice's Necrons wiped me)
Draw - 2 (The 13th hold out in alpha take and hold)