Two-time Pentagon chief had a storied career in government under four presidents, but his vision of a modern US military was unraveled by the long and costly war in the Middle East

Austin would be first Black leader of Pentagon, selected ahead of longtime front-runner Michele Flournoy; move likely to draw opposition over putting ex-military man in post

Expected confirmation would end seven months without Pentagon chief after Mattis resignation; Navy leader Richard Spencer takes over as acting defense chief