“If we know that our own men are in a condition to attack, but are unaware that the enemy is not open to attack, we have gone only halfway towards victory.”
Knowing your side but not the enemy's is only half the picture; completeness needs both.
Chapter 10 begins its knowledge arithmetic: knowing our own men are in condition to attack, but unaware that the enemy is not open to attack, is only halfway towards victory. The verse re-frames readiness as a two-place predicate — your capability and their vulnerability are separate facts requiring separate evidence. Half-knowledge is not half-victory; it is the full distance still to travel.
A startup declares itself "ready to raise" — team sharp, product shipped, metrics clean. The round dies anyway, because readiness was measured on one side only: this particular funding moment’s appetite for its category was closed, and the startup had spent zero cycles assessing that. The soldiers were in condition; the enemy (the market’s openness) never was; the pitch meetings were a very expensive halfway.
Halfway is not a progress milestone — it is a warning state, because the missing half tends to reveal itself at the moment of contact, when adjustment is most expensive. The discipline is evidentiary: readiness claims require two documents, ours and theirs, and the second one is usually the one nobody wrote.