The most brutal massacre by ISIS happened months ago but flew under the radar until now. In August, ISIS fighters took vengeance against the Shaitat tribe in eastern Syria when they resisted the extremists, beheading, crucifying, and shooting more than 700 people in a three day period. It was the bloodiest attack committed by the group to date, and demonstrates that small rebellions inside Syria aren't equipped to take on the powerful militants and are getting little outside help.
