“If his forces are united, separate them.”
Concentrated opposition is hard to beat; fragment it and you face pieces you can handle one at a time.
The catalogue’s structural entry: if his forces are united, separate them. The device targets connection rather than strength — a united opponent is a system, and systems are beaten by cutting their links, not by hammering their nodes. Sun Tzu files it among the stratagems because division rarely looks like attack; it looks like offers, disagreements, and drift.
A standard is contested by a coalition — three companies whose combined weight decides the vote. The challenger cannot out-argue three, so it out-deals one: a royalty arrangement with the smallest member that makes the coalition’s unified position expensive for that member to hold. The abstention that follows is called partnership, not battle — but the coalition is now two, and two is a majority that can be argued with. The whole was never beaten; it was un-wholed.
Separating is not destroying trust in general — the target is the specific bond that makes this opponent stronger than its parts, and the modern translation must stay lawful: no lies, no inducements to breach. What the verse really teaches is attention: most strategists attack masses, and masses are almost always coalitions with seams. Find the seam, price the seam, act at the seam.