What's the appropriate minimum age for this series? My kid is almost 12 and I think that will be ok. But I also realize there is a tame sex scene and I might be desensitized to some of the gore and violence.
You could skip certain episodes, but it would be kind of dysjointed if not viewed in order.
Worst episodes are 6 (Bastogne), 7 (The Breaking Point), and 9 (Why We Fight). 9 is the Holocaust one and also has the sex scene. 6 is very bloody given the focus character is the medic (hospital scene is especially bad as Sanrith noted), and 7's title tells you pretty much all you need to know - features a guy trying to crawl back to his decapitated leg after getting shelled, and Buck Compton succumbing to PTSD.
1 and 10 are mostly safe - 1 has a guy vomiting up food on Currahee after Sobol plays fuck-fuck games with their training, but as I recall that's pretty much it. 10 has the incident where a drunk soldier that runs over another soldier gets pistol whipped by Spiers.
Everything else is somewhere in the middle - off the top of my head, 4 has a German getting bayonetted, although it's mostly discreet and obscured by airplanes. 5 isn't very graphic, but has some psychological horror - Winters having the recurring flashbacks regarding shooting the young German kid. Blithe gets mortally wounded at the end of 3. I believe there is one scene in 8 where a guy gets a faceful of grenade and dies on a table while being held down by a bunch of other guys.
Overall, I would say minimum 14, although depends on your kid's tolerance for violence. If he's been playing M-rated gory games for a while, he might be OK. I personally would probably have not have been OK at 14, but I'm pretty delicate when it comes to super gory shit.