Gen. Charles “CQ” Brown was sworn in as the Air Force chief of staff Thursday, making history as the first African American general to lead a branch of the U.S. military. The oath was administered at Joint Base Andrews, Maryland, by Air Force Secretary Barbara Barrett, and the ceremony also marked the retirement of outgoing Air Force chief of staff Gen. David Goldfein. It followed another ceremony on Tuesday with Vice President Mike Pence at the Oval Office. “This is a very historic day for our nation, and I do not take this moment lightly,” Brown said at Thursday’s ceremony. “Today’s possible due to the perseverance of those who went before…