“After crossing a river, you should get far away from it.”
Once across, distance yourself from the river; lingering at the bank invites disaster from both sides.
Chapter 9’s river rules start with the aftermath: after crossing a river, you should get far away from it. The insight is that transitions leave residue — a force on the bank is neither fish nor fowl, committed to the crossing but not yet to a position. Sun Tzu treats the river’s edge as the most dangerous ground on the march, precisely because it feels like arrival.
A company completes its cloud migration — the crossing — and then lives for a year in the landing zone: dual systems kept "just in case," the legacy team half-dissolved, the architecture half-modern. Every one of those halves is a bank position, and the costs compound monthly. The firms that got far away — one heroic decommissioning month, then fully in the new world — cross the same river once, not forever.
Getting clear does not mean burning the boats reflexively — Sun Tzu keeps bridges when the strategy needs retreat options, and the following verses assume armies cross back. The discipline is against residency: making operational decisions from the threshold, quarter after quarter, because the threshold feels safer than the far bank. Cross, then commit to ground.