Master Sergeant Joshua Wheeler of Roland, Oklahoma, a highly-decorated soldier and father of four, rushed into action when he heard sounds of gunfire coming from a prison in Iraq where dozens of ISIS-held hostage were being held on Thursday.
Those actions, Defense Secretary Ash Carter told reporters on Friday, weren't part of the original rescue mission plan, but were critical to its success.
"I am immensely proud of this young man," Carter said adding that his thoughts and prayers go out to Wheeler's family.
Earlier Friday, Defense officials confirmed to NBC News Wheeler, 39, as the American Delta Force commando killed in a rescue mission in Iraq on Thursday.
Acting on a tip that dozens of ISIS-held hostages were about to be slaughtered, U.S. and Kurdish commandos stormed a prison in northeastern Iraq before dawn Thursday, rescuing the captives in a firefight that ended with Wheeler being shot to death, officials said.
Defense Secretary Ash Carter said Friday that Wheeler "did what proud Americans do" when he ran toward the sound of gunfire.
The operation marked the first known instance of American service members battling ISIS fighters on the ground in Iraq under President Obama's new mission to "train and advise" local forces against the terror group.
Carter said that the military expects "more raids of this kind" and that the rescue mission "represents a continuation of our advise and assist mission."
This may mean some American soldiers "will be in harm's way, no question about it," Carter said.
Wheeler, who earned multiple Bronze Star Medals among others, is the first to die in American combat operations against ISIS. He is survived by his wife and four sons as well as his grandparents.
Wheeler, who was roughly a month shy of his 40th birthday, was born in Roland, Oklahoma. He graduated in 1994 from Muldrow High School in Muldrow, Oklahoma and entered the Army a year later as an infantryman training initially at Fort Benning, Ga., according to a statement from the military.
He was first assigned to Company C, 1st Battalion, 24th Infantry Regiment in Fort Lewis, Washington
In 1997, he transitioned to Company B, 2nd Battalion, 75th Ranger Regiment, Fort Lewis, Washington. Over the next seven years, he worked his way up the ranks from infantryman, rifle team leader, squad leader, weapons squad leader, and anti-tank section leader.
In 2004, Wheeler was assigned to U.S. Army Special Operations Command.
During his military careers Wheeler was deployed at least 17 times — most of those in support of combat operations in Iraq and Afghanistan, the Army said.
Wheeler's awards and decorations for his service were numerous and include four Bronze Star Medals with Valor Device, seven Bronze Star Medals, the Defense Meritorious Service Medal, the Meritorious Service Medal, the Air Medal, the Joint Service Commendation Medal with Valor Device, the Joint Service Commendation Medal, seven Army Commendation Medals, the Joint Service Achievement Medal, eight Army Achievement Medals, the Good Conduct Medal (6th award).
He also earned the National Defense Service Medal with Bronze Service Star, the Afghanistan Campaign Medal with 3 Bronze Service Stars, the Iraq Campaign Medal with six Bronze Service Stars, the Global War on Terrorism Expeditionary Medal, the Global War on Terrorism Service Medal, the Noncommissioned Officer Professional Development Ribbon (3rd Award), the Army Service Ribbon, the Presidential Unit Citation, the Valorous Unit Award (2nd Award), the Ranger Tab, the Combat Infantryman Badge, the Expert Infantryman Badge, the Master Parachutist Badge, and three Overseas Service Bars.
News of Wheeler's death sparked support on social media.
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