Possible Clues:

• Change after a boxing match, as soldiers may be ordered
• Inadmissible act after sailor's change of direction
• Military command: go after crippled U-boat
• Sick spell and sick feeling after a change of policy
• Act of pivoting 180°
• Total change of direction
• Volte-face in rating dated act?
• Attack, following a shock command from the sergeant major?
• An attack leads to shock military command
• A match on square to what Keats referenced to change opinion