Helmuth Hübener, a teenager in Nazi Germany, and also a member of the LDS church, practiced civil disobedience against the Nazis. Two buddies helped him out. Basically, they listened to BBC radio (illegally), found out what was really going on with the war, typed that up, and posted it in public places.
The work these kids were doing was so good that the Nazis, when they finally caught them, were convinced that some adult was behind it all. None was.
The local branch president belonged to the Nazi political party (as most Germans did, at that point in time), and this fact probably helped Mormons from becoming the next Jehovah Witnesses (Jehovah Witnesses were put into concentration camps much like the Jews and gypsies were).
Helmuth Hübener had his head chopped off by the Nazis at the tender age of 17. His two LDS friends were punished and then enlisted in the German army. They both survived and eventually moved to Utah.
Unfortunately, this great example of civil disobedience goes largely unnoticed in LDS circles. It's more well-known in Germany, where Günter Grass, a famous German author, wrote a book about it.
For more information, look up the wikipedia article or find the documentary "Truth and Conviction."
And, in looking at the wikipedia article, I just discovered something totally awesome.
Rumor is that a movie is in the works, starring Haley Joel Osment (the kid from Sixth Sense). Wow. I'm not sure how much of it will be true-to-life, but "Truth and Treason" is definitely a movie to look forward to.