Possible Clues:

• Maj.'s superior
• Rank above maj
• Maj.'s next step up
• Rank above maj.
• Rank for Sen. Tammy Duckworth
• Battalion commander, perhaps: Abbr.
• Silver maple leaf wearer: Abbr.
• Maj., after a promotion
• Blake on 'M*A*S*H,' e.g.
• Henry Blake's rank on 'M*A*S*H': Abbr.