Related Clues:

• Diplomacy alternative
• Peace opposite
• Sherman's hell
• Big fight
• Multi-billion dollar industry
• Ten years' or hundred years' event
• Gettysburg, for one
• Battle of nations
• Sphere of Mars
• "This means ---!"
• Serious hostilities
• In song, it's good for absolutely nothing
• Military engagement
• 'That mad game the world so loves to play,' to Jonathan Swift
• Civil --