They were all killed on the ground and ripped apart, feathers everywhere. The hawk kept returning to feast on the carcass' before I got a chance to find and bury them. They were all in the woods in the underbrush and were hard to spot. The EE was the same color as the tress and the Barred Rocks were black on white. The bantam is white, she was easy to spot, and survived by scurrying under the briars making it difficult for the hawk to get in and finish her off.
Cover helps as you noted. A dog is even better but may not be applicable to your situaton. I still recommend upgrading rooster and if attack occurs again, make every effort to photograph hawk on chicken. I for one would like to see evidence of red-shouldered tackling a standard sized chicken.