The video of US marines urinating on Afghan corpses was deemed "too shocking" to be shown on the BBC news last night, which raises the question as to what exactly is shocking about it. Is it the ritual humiliation of dead enemies (we can assume they were combatants, or at least victims, rather than random corpses discovered while taking a stroll), or is it pissing in public?
The desecration of enemy corpses has being going on since prehistory and it would be naive to believe that it is going to stop any time soon. That said, such rituals clearly change over time to reflect prevailing norms. We no longer stick our enemies' decapitated heads on pikes, positioned over the gates of the city, instead we organise decorous parades (it's interesting to note that the last victory parade in London, for the Falklands War in 1982, marched into the City via Moorgate).
Pissing on a corpse is pretty trivial in historic terms. Though it qualifies as a war crime, it hardly compares with cutting off genitals, ears, noses or scalps. Indeed, one can argue it is less effective as a deliberate humiliation than pissing on your enemies while they are still alive.
So why the shock? Perhaps because these particular marines have broken through the veil and thus undermined our carefully constructed delusion that Afghanistan is a mission of pacification, in the same way that Abu Ghraib and other abuses undermined our belief that we were liberating the Iraqi people. It is for this (i.e. letting the cat out of the bag) that they will be punished.
Perhaps also there is embarrassment at the sexual overtones of the act. The reference to "golden showers" and the porn-style mise-en-scene (multiple, laughing men standing around prostrate victims with their cocks out). Despite this queasy, modern tang, there is also a sense of something more ancient and rank here. These could have been Macedonians from the army of Alexander.
There is an excellent cartoon on the subject by Steve Bell in today's Guardian, essentially a piss-take on the famous raising of the Stars and Stripes by US Marines at Iwo Jima in WW2. This is resonant precisely because Bell is treating the act, albeit ironically, as a ritual of victory.