“In war, the way is to avoid what is strong and to strike at what is weak.”
Do not charge the point where your opponent is strongest. Find the gap, the underserved niche, the weakness, and direct your limited resources there. Small forces win by choosing favorable ground, not by outmuscling the incumbent.
This is Chapter 6’s thesis compressed into a single rule — the chapter is literally named for it. Sun Tzu has just shown that an army may be prevented from battle by defending everywhere it is strong, and draws the operational conclusion: your effort goes where the defense is thin. The verse pairs with the one about water finding the low ground: force, like water, flows to the point of least resistance, and that is a choice, not an accident.
A two-person firm cannot out-advertise the incumbent in the incumbent’s strongest segment, so it doesn’t try. It maps where the giant is structurally slow — a niche too small for its margins, a region its distributors ignore, a customer type its sales scripts annoy — and becomes excellent there instead. Five years later the niche is "the two-person firm’s market," and the incumbent would now pay more to enter it than to build it.
The lesson is about where to direct force, not who to bully. Striking weakness means choosing the point of engagement for strategic reasons; it never means hunting the weak for sport — Sun Tzu’s economics are about winning cheaply, and cheap wins come from ground, not from cruelty.