Possible Clues:

• Hit song by ABBA
• One leaving someone on standby to search endlessly for battlefield?
• Where Napoleon did surrender, according to 21
• Abba song in can following number one?
• Famous battle
• A final crushing defeat
• The battle that marked the end of the Napoleonic Wars
• Battle later lost in court
• Downfall of criminal later put in court
• At last, action stations!