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Interior vs Exterior Lines

Why It Matters

Interior position enables concentration through mobility. Exterior position enables simultaneous pressure but requires more total force and coordination.

The Key Move

Ask: am I interior or exterior? If interior, use mobility to concentrate sequentially against dispersed enemies. If exterior, coordinate to apply simultaneous pressure that prevents enemy concentration.

Classic Application

Germany in both World Wars faced enemies on multiple fronts (exterior lines against Germany's interior). Germany's strategy relied on interior lines to defeat enemies in sequence before they could coordinate effectively.

Surprising Application

Multi-front competition. A company facing multiple competitors can use interior position to focus sequentially - address one threat, then pivot to another. Competitors must coordinate (hard) to apply simultaneous pressure.

Failure Modes

  • Interior force trying to defend everywhere (surrenders mobility advantage)
  • Exterior forces attacking sequentially (defeated in detail)
  • Misjudging which position you're in

Go Deeper

Jomini on lines of operation. Napoleonic campaign analyses.