Question: United States Forces – Iraq (USF-I) was an American military sub-unified command, part of U.S. Central Command, General Lloyd Austin served as Commanding General, he was the which number commander of United States Central Command (CENTCOM)? 
Sentence (from "United States Forces – Iraq"): USF–I replaced the previous commands Multi-National Force – Iraq, Multi-National Corps – Iraq, and Multi-National Security Transition Command – Iraq from January 2010.
Relevant evidence: No