The topmost line takes the hexagram's brightness out of doors. Legge's translation has the king employing the subject in his punitive expeditions, where he achieves admirable merit, breaks only the chiefs of the rebels, and does not punish those prisoners who were not their associates, and the outcome is no error. The commentary on the image says the object is to bring the regions to a correct state, which limits the undertaking to correction rather than to conquest.
The distinction between chiefs and followers is the content of the line, and it is a legal distinction belonging to the period the text comes from rather than a modern scruple read back into it. A punitive expedition against a rebellious region was an instrument of Zhou royal government, and the text specifies how far it may go: to the leaders, and no further. What is praised is the discrimination, and a bright figure ends here because discrimination is what light is for.
The stroke is strong in an even seat, incorrect by the ordinary rule, at the very top of the upper trigram Li. Extremity of position is where most hexagrams show things going wrong, and the classic usually distrusts a strong line at the summit. Here it is given a task in which force is legitimate and then bounded by clarity, which is the only shape under which this hexagram will approve of force at all.