Final answer:
In the military strategy context provided, 'penetration' means advancing or moving into enemy territory deeply to maintain cohesion among invading forces.
Step-by-step explanation:
Regarding the question about the meaning of "penetration" in the context of the provided text, it refers to 'penetrating deeply brings cohesion; penetrating but a short way means dispersion.' Here, penetration implies advancing or moving into a territory or area.
The context is military strategy, where a deep penetration into enemy territory results in the cohesive movement of forces, whereas a shallow penetration leads to their dispersion. This fits option 2, being familiar in a country, in military terms, of establishing a presence or securing an area deeply within enemy territory.