World War II Resistance Movement Communication Methods
Stakeholder Mapにより

1. Secret Codes
1.1. Methods
1.1.1. Coded messages in newspapers
1.1.2. Invisible ink
1.2. Purpose
1.2.1. Conceal plans from occupying forces
2. Couriers
2.1. Methods
2.1.1. Human couriers on bicycles or on foot
2.1.2. Messages hidden in clothing
2.2. Purpose
2.2.1. Transport messages across enemy lines
3. Radio Transmissions
3.1. Examples
3.1.1. BBC broadcasts to French Resistance
3.1.2. SOE radios (UK)
3.2. Purpose
3.2.1. Coordinate attacks and sabotage
3.2.2. Relay intelligence to Allies
4. Dead Drops
4.1. Methods
4.1.1. Hiding messages in common locations
4.1.2. Drop zones like hollow trees or walls
4.2. Purpose
4.2.1. Conceal message exchanges from enemy surveillance