Related Clues:

• Battle of nations
• Sphere of Mars
• Ongoing trouble
• "This means ---!"
• Alamo event
• Serious hostilities
• In song, it's good for absolutely nothing
• Persistent attack
• WWII Leningrad event
• 'That mad game the world so loves to play,' to Jonathan Swift
• Civil --
• Sun Tzu's 'The Art of ___'
• It can cause a draft
• Gen. Sherman called it hell
• Prolonged assault