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)? 
Context: The Fifth Fleet is a numbered fleet of the United States Navy.  It has been responsible for naval forces in the Persian Gulf, Red Sea, Arabian Sea, and parts of the Indian Ocean since 1995 after a 48-year hiatus.  It shares a commander and headquarters with U.S. Naval Forces Central Command ("NAVCENT") in Bahrain.  s of 2017 , the commander of the 5th Fleet is Vice Admiral John C. Aquilino.  Fifth Fleet/NAVCENT is a component command of, and reports to, U.S. Central Command (CENTCOM). Lloyd James Austin III (born August 8, 1953) is a retired United States Army general.  He was the 12th commander of United States Central Command (CENTCOM).  Austin was the first African American to head the organization.  Prior to his assignment in CENTCOM, Austin served as the 33rd Vice Chief of Staff of the United States Army from January 31, 2012, to March 8, 2013.  His assignments prior to CENTCOM were as the last Commanding General of United States Forces - Iraq, Operation New Dawn, which ended on December 18, 2011, and then Vice Chief of Staff of the United States Army.  On December 6, 2012, the Pentagon announced that President Barack Obama had nominated Austin to lead the U.S. Central Command.  Austin was confirmed by the U.S. Senate on March 5, 2013, and assumed command on March 22, 2013.  On April 5, 2016, Austin's retirement ceremony took place at Joint Base Myer–Henderson Hall.  He received the Defense Distinguished Service Medal, the Army Distinguished Service Medal, the Defense Superior Service Medal, the Legion of Merit, and others. The Commander, U.S. Marine Corps Forces, Central Command (COMUSMARCENT), is designated as the Marine Corps service component commander for Commander, U.S. Central Command (COMUSCENTCOM).  MARCENT is responsible for all Marine Corps Forces in the CENTCOM Area of Responsibility (AOR), except for those assigned to the U.S. Special Operations Command (USSOCOM), and Special Operations Command, Central Command (SOCCENT). Jay W. Hood is a retired United States Army Major General.  His final assignment was as Chief Of Staff of the United States Central Command.  His previous assignments include Commander of First Army, Division East, Fort George G. Meade, Maryland Commanding General of Joint Task Force Guantanamo (JTF-GTMO), Guantanamo Bay, Cuba; Assistant Division Commander (Forward), 24th Infantry Division and Deputy Commanding General (South), First Army, Fort Gillem, Georgia; Commander, 82nd Airborne Division Artillery and Commander, 3rd Battalion, 319th Field Artillery Regiment, 82nd Airborne, Fort Bragg, North Carolina; Commander, Battery D, 4th Battalion (Airborne), 325th Infantry (Battalion Combat Team), U.S. Army Southern European Task Force; and Commander, Battery A, 2nd Battalion, 321st Field Artillery Regiment, 82nd Airborne Division, Fort Bragg, North Carolina.  General Hood is a graduate of Pittsburg (KS) State University Raymond Thomas "Ray" Odierno ( ; born 8 September 1954) is a retired United States Army General who served as the 38th Chief of Staff of the Army.  Prior to his service as Chief of Staff, Odierno commanded United States Joint Forces Command from October 2010 until its disestablishment in August 2011.  He served as Commanding General, United States Forces – Iraq and its predecessor, Multi-National Force – Iraq, from September 2008 through September 2010.  Before then, he served as Commanding General, III Corps, from May 2006 to May 2008.  Odierno is the twelfth American military officer to command at the Division, Corps, and Army level during the same conflict and only the second with this distinction since the Vietnam War.  Before commanding III Corps, he served as Assistant to the Chairman of the Joint Chiefs of Staff in Washington, where he was the primary military adviser to Secretary of State Condoleezza Rice from 3 November 2004 to 1 May 2006. Mark Irby "MRT" Fox (born March 1, 1956) is a retired United States Navy Vice Admiral who last served as the Deputy Commander of United States Central Command.  Prior to assuming his duties at CENTCOM, he served as Deputy Chief of Naval Operations for Operations, Plans, and Strategy (N3/N5), Commander, U.S. Naval Forces Central Command (COMUSNAVCENT) and Commander, U.S. 5th Fleet (COMFIFTHFLT).  He also previously served as the Commander of the Naval Strike and Air Warfare Center (NSAWC) at Naval Air Station Fallon, Nevada, and as Communications Division Chief, American Embassy Annex, Baghdad, Iraq. United States Forces – Iraq (USF-I) was an American military sub-unified command, part of U.S. Central Command.  It was stationed in Iraq as agreed with the Government of Iraq under the U.S.–Iraq Status of Forces Agreement.  USF–I replaced the previous commands Multi-National Force – Iraq, Multi-National Corps – Iraq, and Multi-National Security Transition Command – Iraq from January 2010.  General Lloyd Austin served as Commanding General.  The logo of the USF-I depicts a lamassu. John Philip Abizaid (born April 1, 1951) is a retired United States Army general and former U.S. Central Command (CENTCOM) commander, overseeing American military operations in a 27-country region, from the Horn of Africa, the Arabian Peninsula, to South and Central Asia, covering much of the Middle East.  CENTCOM oversees 250,000 US troops.  Abizaid succeeded General Tommy Franks as Commander, USCENTCOM, on July 7, 2003, and was also elevated to the rank of four-star general the same week.  He was succeeded by Admiral William J. Fallon on March 16, 2007. Robert William Cone (March 19, 1957 – September 19, 2016) was a United States Army four-star general who last served as the commanding general of U.S. Army Training and Doctrine Command.  He assumed command of TRADOC on 29 April 2011.  He previously served as the commander of Fort Hood and III Corps on 22 September 2009 where he also deployed to Iraq in February 2010, and served as the Deputy Commanding General for Operations, United States Forces – Iraq, until February 2011.  Prior to that, he served as the Special Assistant to the Commanding General of U.S. Army Training and Doctrine Command in Fort Monroe, VA.  He retired in 2014. Martin Edward Dempsey (born March 14, 1952), sometimes known as Marty Dempsey, is a retired United States Army general who served as the 18th Chairman of the Joint Chiefs of Staff from October 1, 2011 until September 25, 2015.  He previously served as the 37th Chief of Staff of the Army from April 11, 2011, to September 7, 2011.  Prior to that, he served as Commanding General, U.S. Army Training and Doctrine Command, from December 8, 2008, to April 11, 2011, as Acting Commander, U.S. Central Command, from March 24, 2008, to October 30, 2008, as Deputy Commander, U.S. Central Command, from August 2007 to March 23, 2008, and as Commanding General, Multi-National Security Transition Command – Iraq (MNSTC-I), from August 2005 to August 2007.  Dempsey assumed his assignment as Chairman of the Joint Chiefs of Staff on October 1, 2011 and stepped down from the Chairmanship on September 25, 2015.  He now serves as a professor at Duke University.
Answer: 12th