What is the moral of the book?

I don't know if there is a specific moral to this book but I can comment in terms of theme. Understanding and learning from history would be the predominant take away from the book. Harry Truman's quote "Those who do not read and understand history are doomed to repeat it" is very pertinent to this story. The similarities between the Philippines, Vietnam, and even Iraq cannot be ignored. The common traits are: a country being occupied where natives yearn for autonomous rule, not being able to fight conventionally, public opinion waning, and mounting atrocities. Major conventional "battles" soon cease to take place, because the lesser-armed force will not just stand up and fight as in typical battle scenarios. They use trickery and duplicity to terrorize troops who more and more can't tell friend from foe. Seeing their buddies killed in senseless acts of violence, the troops become desensitized to the situation, and the atmosphere for atrocities becomes ripe. The atrocities often escalate, as they did in the Philippines, Vietnam and Iraq. In all three situations, American soldiers were caught in the fervor or revenge. The public saw atrocities committed and American soldiers punished. The condescending idea of exporting America is another trait of all three situations. Some countries don't want to be "America East." Others might want American improvements, but resent the way they are treated. The blatant racism and superiority are other common elements to the Philippines, Vietnam and Iraq.