I read the book years ago. Was disappointed when they didn't tell the complete story of the horrors that those guys went through trying to get to the next LZ. (Wasn't there a third LZ too?) I forget the reasoning they marched on rather than just flying out of LZ Xray.
There was also the story of a guy that had got separated from his group as they marched out and got ambushed. He circled around and up a hill, and could hear the NVA shooting our wounded. The guy walked out days or weeks later on his own iirc.
Yes there was LZ Columbus. I know a guy that was in the 2nd Battalion 5th Cav. that marched to Columbus. He was also involved in the rescue of the lost platoon.prior to that.
No one admitted to ordering the dividing of the troops and the march out instead of withdrawing everyone by helicopter.