The problem was not that Black Kettle misjudged who his allies were.

The problem was that his allies — the people within the American system who genuinely wanted peace — did not have sufficient power to prevent their opponents from attacking his camp.

The structural lesson of this failure is important: the existence of good faith within an adversary’s political system does not guarantee that good faith will determine policy.

The people of good faith have to have sufficient power to impose their position, or their good faith is insufficient protection for those who trust them.

Black Kettle trusted the right people.