The Underground Railroad, a vast network of people who helped fugitive slaves escape to the North and to Canada, was not run by any single organization or person. Rather, it consisted of many individuals -- many whites but predominently black -- who knew only of the local efforts to aid fugitives and not of the overall operation. Still, it effectively moved hundreds of slaves northward each year -- according to one estimate, the South lost 100,000 slaves between 1810 and 1850.
http://www.pbs.org/wgbh/aia/part4/4p2944.html
I believe todays war in Iraq is an exception to the rule, and is being waged for moral reasons, to free people from the bonds of dictatorship, and set an example for other Arab countries the can prosper under a republic that respects individual rights.
I believe Vietnam was also fought for moral reasons, to stand up to communism, the killing in Cambodia after we walked away, shows the true evil we were against. The money that started / really fired up things in Vietnam was French, with France wanting to reclaim what they thought was theirs to plunder.