Our Leaders' Lessons from Vietnam

The wrong one, of course. The correct lesson is to choose your wars properly i.e. limit yourself to necessary wars.

And then there's Iraq. Was any war less necessary?

But then, this is what the wingnuts learned from Vietnam. Their dementia is clear. This what Rummy learned:

Today the centers of gravity of the conflict in Iraq and the global war on terror are not on battlefields overseas. Rather, the center of gravity of this war are on the centers of public opinion in the U.S. and in the capitals of free nations

Link.