31 US troops killed in destruction of Fallujah
According to Slate. So, ignoring the huge negative implications of storming a city and tromping through mosques and such, the Marines are now in charge of a huge chunk of depleted-uranium-soaked rubble, approximate value in bringing peace and freedom to Iraq--$0. So $0 divided by 31 soldiers--approximately $0 per life lost. The benefits per life lost for Iraqis were much lower.