This is partially based off the movie, though not seen recently, and the various write ups around the real ops, though i have not read the book.
As you are aware, the movie is based on a book, which is one persons account of a real event.
.. why didn't they just hold the high ground up the mountain and call for an extraction? It seems like a critical mistake to move down the ridge and have all the Taliban above their heads.
Movie-wise, they were not on the high ground in the first place. Their mission plan had taken them down off the high mountains and on to some lower ground, that was still high above the named area of interest. After having been compromised they are making their way to higher ground, in order to get comms - they couldn't get comms in their former overwatch position.
What they found as they crested a hill was that it was a false summit, they thought they had gone to a high point but it was surrounded by yet higher points that blocked their comms further.
They decided to rest, not knowing at this point that the ACM had been alerted and were heading towards their position undetected.
By the time they are detected by the team, they are surrounded, and the anti-coalition militias (ACM) already have the high ground all around them. They have no choice but to choose the route of least resistance and least incoming fire, which happens to also be the hardest terrain too.
Essentially the ACM were above their heads already - they would have had to fight their way to the high ground, but against overwhelming odds.
Also, IIRC, the extraction point - maybe both, had already been either overrun or compromised.
Had they held the high ground and made a safe perimeter, they could have used the radio or satellite phone.
Yes, but easier said than done - in real life the terrain is tough, from personal experience the country is pretty, but very tough terrain in the high regions. The team had a lot more kit than the ACM, who were a lot lighter on their feet, them having the home advantage, and were able to advance quickly over difficult terrain - faster than the SEAL team could.
safe perimeter? Theres just four, with limited weapons and ammo, against, according to the movie, maybe 150, with more ammo and more variety of weapons.
I mean really, this feels like saying why didn't the Titanic just change direction and avoid the iceberg. Issues aside regarding the accuracy of the account (and there are a lot, apparently the 'vote' never happened and was ghost written in) in the first place, the main points of this event actually happened in real life and I don't think they were just going to change for the sake of a plot point.
In real life, luckily for Luttrell, they were forced down the right valley. The eastern valley enjoyed rather warmer relations with the coalition, due to previous efforts at establishing schools and medical facilities, whereas the outcome might have been worse if they had been forced west, towards korengal.
Rough map guide to the real thing:
This second rough map, overlaid with the one from above, gives a better understanding of the terrain they fought in.
Their approach from MH-47 insertion was from the south, between the two high mountain range peaks, Gatigal and Sawtalo. This was the high ground.
Another view showing the approach after insertion, which was on the high ground (around 9000ft), going lower for observation (to the west) and subsequent soft compromise, then the drop down to the valley (to the north east) and refuge. According to other notes, the SEAL team was already compromised by the noise of their insertion on the mountain ridges, and the ACM already occupied the high ground, looking for the team (having allegedly found the ropes that the team used).
That the rescue attempt plan was to insert the SEALS on the mountain ridges, hoping to fight downhill to where they thought the SEAL team was, meant that they did not know that the high ground was already compromised. The loss of a MH-47 and everyone aboard was subsequently depicted in the movie.
IRL v movie:
The three-phase plan called for inserting a four-man SR team the first night, then inserting the second element of SEALs the following night to establish an isolation zone around Shah. Finally, 150 U.S. Marines would come in to establish blocking positions for the SEALs' assault on Shah's compound.
The Night Stalkers' job was to insert the SEALs on a ridgeline where the terrain left few options for landing zones. The commandos would have to descend from a rope — fast-rope — while the helos hovered high above the trees. That meant if the SEALs got into trouble, extraction would potentially require the use of a hoist to pull the SEALs out, which was a time-consuming and dangerous option.
"This was a desolate part of the Hindu Kush, and at night, you wouldn't really expect to see much," "Not really sure who they were, but there was more activity than I expected."