This could be an interesting competition.
The 2010 Consequence Prize in Poetry will be awarded for the best poem addressing the culture and consequences of war. Far be it from me to advise entrants but I wouldn't really see much of a point in submitting a pro-war poem.
Massachusetts based journal, not a large prize but the topic is thought-provoking, there's no sign of any line limit, you can enter online and, bless their cotton combat jackets, the competition is FREE...
Full details here