The link in the OP provides SOME of these answers (they describe how each fatality occurred)
As I posted earlier, my son is a Marine infantry corporal; his second time in Iraq – this time a volunteer (he was due to be discharged, but extended so he could return with his battalion).
He and his cohorts deeply believe in the mission. I see that many posters here don’t, either that the war was misconceived to begin with, or that it is now a lost cause.
From what my son says, the American military there mostly don’t agree.
When I asked why he wanted to go back, he told me this. After the war March-April 2003, his battalion was assigned to Al Hilla, a city of some 500,000 people. He spent his time training the new Iraqi police force, building schools, and providing security for the newly formed local government. His unit discovered the killing fields outside of Hillah. He saw personally the torture chambers. He became deeply committed to the Iraqi people whom he met and worked with in his five months in Hillah. He felt he made a real difference in their lives. He made life long friends.
I have great trepidation about my son being there. He was in the battle in Najaf, and was in bitter firefights often. He believes deeply in his mission, enough to risk his life. I wish I were in his place, but I am too old. I was a Marine 30 odd years ago; I wish I were in now, instead.