User blog comment:Garhdo/Extended Cut - opinions?/@comment-99.236.226.219-20120627231540/@comment-1221773-20120628031315

I believe it's mentioned during the mission that only around 50% of the Hammer ground forces make it through the Reapers' anti-air defenses and land on Earth. That's a pretty high mortality rate any allied landing craft, and I think the numbers are even worse if you have a lower-than-optimal EMS.