Unifying Influences

I went on a fieldtrip on Satuday to more or less the middle of no where.We went off roading in 12 passenger vans... and got stuck. It took perhaps an hour, hour and a half to get both of our vans unstuck and back on a firmer road. We only had 2 shovels (but at least we had them) and we hauled flattish chunks of limestone from the nearest rock outcrop to use as planks to put under the tires. For the most part it went fine and people stayed good natured but at a few moments there was some argument and under the breath mutterings of stupidity (if they had just listened they would have known why certain things were being done). "Too many cooks in the kitchen," as someone noted.
It actually wasn't an uncommon concurrences for these poor geology vans or so I've heard.

This picture really doesn't give it justice.

Not long ago I was talking to some geology students about how close everyone seems to be in the geology department, I've heard or been part of such a tight knit university department. One of the students I was talking to explained it simply. "It's the fieldtrips." Which I think refers to both the time spent together (with more time you are more likely to become friends), but I think also to sharing hard experiences.
In High school I wrote a research paper entitled "Boosting a Nation's Self-Esteem: The Impact of the 'Space Race' on American Nationalism." Then, in my novel "Legend Speaker" I wrote about a girl who tries to unify a series of nomadic hunter-gatherer groups. When trying to figure out how to make that possible for my characters to accomplish I had a discussion with my brother and we talked about how there are three main ways to accomplish unity on the large scale.
1)A disaster like Hurricane Katrina.
2)A common enemy like most wars or more specifically 9/11.
3)A common goal such as winning the most medals in the Olympics.
The problem though is most of these are high stress situations, and as shown in the minor example of the fieldtrip that can lead to argument and tension. There are plenty of examples of high stress situations leading to the exact opposite of unity, so the question is when do they cause unity and when divisiveness. There seems to be something about success in the endeavor that lends itself to unity in the end but that might just be a circular argument.