Army Chief of Staff Gen. George Casey congratulates Pete Geren. Army Chief of Staff Gen. George Casey (left) congratulates Pete Geren on his appointment as Secretary of the Army in the Pentagon on Aug. 30, 2007. Geren was sworn-in as the 20th Secretary of the Army by Secretary of Defense Robert M. Gates. SHARE: Download: Full Size (0.03 MB) Credit: VIRIN: 574551-Q-XQY53-215.jpg Photo Gallery