Montaigne's main idea here is that a display of courageous resistance can shake us out of our anger more effectively than pleas for mercy and acts of supplication.
The main idea stated at the outset:
The most usual way of appeasing the indignation of such as we have any way offended, when we see them in possession of the power of revenge, and find that we absolutely lie at their mercy, is by submission, to move them to commiseration and pity; and yet bravery, constancy, and resolution, however quite contrary means, have sometimes served to produce the same effect.
A funny sketch reminiscent of a story from an ancient Chinese history text:
...the ladies and gentlewomen only who were in the town with the duke might go out without violation of their honour, on foot, and with so much only as they could carry about them.
Whereupon they, out of magnanimity of heart, presently contrived to carry out, upon their shoulders, their husbands and children, and the duke himself; a sight at which the emperor was so pleased, that, ravished with the generosity of the action, he wept for joy, and immediately extinguishing in his heart the mortal and capital hatred he had conceived against this duke, he from that time forward treated him and his with all humanity.
Montaigne points out that this isn't to be taken as an absolute rule:
Man (in good earnest) is a marvellous vain, fickle, and unstable subject, and on whom it is very hard to form any certain and uniform judgment.
See Montaigne, "That Men By Various Ways Arrive At The Same End".