Six at the top, as a changing line, marks the point where a well established peace begins to revert toward the disorder it once replaced, the city wall falling back into the moat it was raised from. A querent shown this line is warned against using force to hold the situation together, since Legge's text is explicit that this is not the time for the army, and is counseled instead to keep order only within what remains directly one's own, accepting that some regret is unavoidable even for firm and correct conduct here.
Flipping this line changes the upper trigram from Kun to Gen, Mountain, giving Gen over Qian, the hexagram called Great Taming. The collapse of a wall back into its moat gives way, on the far side of change, to a hexagram of accumulated strength restrained by something as solid and enduring as a mountain, the very structure that just gave way replaced by a far more stable form of holding. The movement suggests that what looks like final decline can, once changed, become the ground for a sturdier, more deliberately restrained accumulation than the peace that has just ended.
As the final line of Peace's arc, this position closes the hexagram's whole movement from rising connection to established harmony to eventual reversion, the natural end that even heaven and earth's communication cannot indefinitely postpone. A reading falling here suggests the present phase is ending, and that what follows, rather than repeating the collapse, may instead be built on firmer, more consciously restrained ground.