President Donald Trump announced on Friday he was naming his Secretary of Homeland Security John Kelly to be the next White House Chief of Staff, replacing Reince Priebus.

Here are five facts you should know about Kelly:

#1: John Kelly is a retired four-star Marine general who last served as the commander of U.S. Southern Command, which oversees U.S. operations in Central and South America and the Caribbean. He became President Trump’s Secretary of Homeland Security on January 20.

#2: Kelly served three tours in Iraq, commanding as a two-star general from 2008 to 2009. He commanded a Marine task force as a one-star general during the initial assault into Iraq. Asked then by a Los Angeles Times reporter if he was concerned about Saddam Hussein’s forces, he reportedly said, “Hell these are Marines. Men like them held Guadalcanal and took Iwo Jima. Baghdad ain’t sh-t.”

#3: Kelly’s eldest son, Marine First Lieutenant Robert Kelly, was killed in action in Sangin, Afghanistan, while leading a platoon of Marines on a patrol. Kelly is the highest ranking military officer to lose a child in Iraq or Afghanistan. He has another son serving in the Marine Corps.

#4: As a Marine general during the Obama administration, he opposed opening combat jobs to women in the Marine Corps, and closing the Guantanamo Bay detention facility. He rejected the argument that the prison served as terrorist recruitment propaganda as nonsense. He told Defense One: “Bombing the living sh-t out of ISIS in Iraq and Afghanistan, Syria, that would maybe irritate them more than the fact we have Guantanamo open.”

#5: He is 67-years-old, and was born in Boston. Kelly enlisted in the Marine Corps in 1970, and became an officer in 1975. He retired in 2016, after serving 40 years in the Marine Corps. He’s a graduate of the University of Massachusetts, Boston, and received a Master’s degree from Georgetown.