Matt's citation of the attack on Sumner by Brooks is certainly apt; it is parallel not only in the role of honor in motivating the attack, but also in the public, political setting (council of the Greeks, the U.S. Senate), and in the far-reaching effects of the antagonism.  Brooks's attack was so violent, the news coverage so inflammatory, and the public reaction so fierce, that it is thought to have helped accelerate the tensions leading to the Civil War. 

Here is a link to an outstanding account of contemporary combat-- it is an article in The Telegraph excerpted from journalist Sebastian Junger's book War.  Despite the differences in modes of warfare between the ancient Greeks and the 21st century wars in Iraq and Afghanistan, the behaviors of the warriors and the psychology of war are uncannily alike.