The NCR don't need to capture Flagstaff to win the war. If Caesar dies and the legion fractures, that suits them just fine. The Allies never captured Berlin in WW1.
Sure thing. Caesar is his own faction's weakness and his death would plunge his legions into turmoil. Thing is, in the case of a Legion's victory over Hoover Dam, Caesar has probably had his tumor surgically removed.
And of course, a defeat of California would force the Legion to mutate in radical ways to not fall into stagnation and chaos, but that's what Caesar wants in the end.
As for Germany, the context was very different. The germans had planned a -very- short war, economically speaking, and were crumbling under debts by the end. Secondly, they were being squeezed from the west as much as from the east. They had to resort to melting church bells to keep making artillery shells. The population was starving due to diverse blockades at all borders.
None of that could happen for Caesar's turf. If the Legion's economy is also based on the Augustus' Roman one, then the more it fights, the richer it gets. Caesar doesn't rely on the support of foreign nations so wouldn't care if anyone blocked his borders (also, who could blockade New Mexico & Colorado, even today? Those are huge borders) He doesn't need much of an industry to keep a war afloat, considering his men's equipment, and even if he did, he has slaves to put to work.
As long as he lives, Caesar could stand a war for a very long time -even a sterile one- while the NCR would need peace in the short term to simply continue to function.
And the more the legion get pushed back, and the longer the NCR hold the Mojave, the harder it gets for the Legion. If the NCR entrench and consolidate, it gets harder for the Legion to cross with every attempt.
-If- the NCR entrenches and consolidates. Which seems unlikely, considering that even while facing an existential threat at its borders, the NCR keeps sending conscripts with low morale and supplies so low, they don't even get a standard uniform anymore. Local support is very low and wouldn't get better if the NCR had to keep fighting in that foreign land.
They held Hoover Dam for years after their first victory, knowing that the Legion would come back, eventually. Still, they didn't consolidate much except for the Mojave Outpost because they simply cannot, with the current government that keeps prioritizing the protection of brahmin barons instead of the borders.
It's the second attempt for the Legion at Hoover Dam. Still, their morale is way, way higher than the NCR's. Nothing indicates that the Legion wouldn't push again, even with heavy losses. Same couldn't be said for the Republic, in its current state.
And if the legion wastes all its resources on Hoover Dam it leaves itself open to internal revolt and external forces.
We don't really know what's east of the Legion's territory, true, but Caesar is pretty clear that the NCR is the one and only force that could match him. The conquest by another power is pretty unlikely.
Same goes for the internal revolt. This is a fucked up feudal society, with a brainwashed population and a big focus on radical justice and security. People wouldn't revolt there as easily as they would in a republican, modern society, considering that any attempt would lead to the cross. They have lived that way for decades of non-stopping conquests and as far as we know, the legion's society is still pretty stable.
The NCR on the other hand absolutely needs a quick victory to keep social stability. The possibility of a revolt seems more likely in the west than in the east, considering the current morale of the conscripts and the propaganda efforts Kimball deploys, just to prevent desertion and turmoil in his ranks.
There's 200km of desert with the Sierra Nevada protecting the northern flank.
Is that really a protection, though? A desert cannot be secured by an army, even today. -If- the Legion manages to cross the Long 15, once they reach the desert they'd be very hard to fight. While it's true that a trench war would be the end for the Legion, it's impossible to deploy a defense line it in such a big area, where hundreds of men can walk around unnoticed. This is what makes the war in Syria very difficult for the infantry, for example. Militias can move and hide easily.
200km of desert could be crossed in one day by a motorized army. For the Legion, let's be pessimisstic and give them one week.
Once the Mojave falls, their armies are one week from the Hub, max, with nothing in their way.
If the Mojave falls to the NCR, on the other hand, they still present no existential threat to the core power of the Legion. The Legion's only threat at this point is itself, due to Caesar's tumor, but that's independent from the Republic.
Even getting past the Mojave Outpost would be a nightmare for the Legion. Getting up that hill if the NCR set up artillery and machine gun emplacements? They'd lose thousands.
Unless the Legion has a working bomber -the outpost having no air defense- and artillery ready. Which they'd have, at this point.
Also, the outpost is occupied by conscripts led by a man who loses all hope once the Legion takes over Nipton. Not a good sign. Their supplies are low and the civilians they are surrounded with are caravaneers ; according to Cass, they'd be perfect candidates for joining the Legion willingly. Which exposes the outpost to risks of terrorist attacks, exactly like for the strip embassy. A chemical attack at the beginning of the assault is very likely, since this is the strategy used by the Legion when they attack the Dam.
If the outpost doesn't surrender, then only the Legion could decide to throw some foot soldiers to finish them. Considering their cruelty, they'd probably use child soldiers, to put a final blow to the conscript's morale. If that's not enough to provoke mutiny and desertion in the outpost, then only, they could send soldiers.
And as Ben Soto has said, the closer the Legion get to the Core Region, the better the NCR's infrastructure. They've got railways to move troops and supplies in the West. The legion are using brahmin.
That's true. But the Legion doesn't need to fully invade California.
Isolating the Hub cuts it in two, cripple its finance, morale, commerce etc. And if Caesar manages to take the city, he can keep the population hostage to prevent the NCR from unleashing its full military power. Add some turmoil in the north thanks to tribal auxiliaries, and you've got the NCR in a very bad situation, no matter how intact their military and infrastructure is.
At this point, a conditional surrender is totally plausible. The NCR would rather negociate a vassal-state, status-quo situation rather than risking an escalation and a full-scaled trench war that could last for years, in their own territory (which would leave the Republic in ruins, even if they'd win). Caesar would be forced to accept, considering that he doesn't want his invasion to take too long. And because he knows that the NCR would beat his bald ass eventually.
The Brotherhood are a spent force.
I'm talking about the Californian brotherhood, not the Mojave's. The californian brotherhood has been waging war with the NCR for years, and has no intention of giving up.
At the second the NCR shows any weakness, you can bet the brotherhood will seize the opportunity.
Sure, they would never accept Caesar's rule. But if they want to survive, they know that their odds are better against the Legion than against the NCR.
We know nothing about the tribals in California now. It's a bit of a stretch to say Caesar would find it easy to assimilate them.
Well we know that Bullhead was full of tribes until Kimball seized it. Cass and Raul keep saying that the roads in California are not safe, because of the constant brigandage, so it's safe to say that there are plenty of little factions here and there.
It's not like the Dead Horses and the Sorrows have jumped at the chance of joining.
The Dead horses were actually part of Caesar's Legion, so they did join them at some point, but I don't remember why they aren't members of it anymore, by the time the DLC takes place. The white legs jumped at the chance of joining Caesar. Same for the fiends, and the bombers don't hesitate for long, simply because they don't know about the Legion's activities. They are a tribe, their knowledge of the geopolitical struggles is limited to the immediate perception.
But first they have to get to Shady Sands. I suppose Caesar could go full Hannibal Crossing the Alps on the Sierra Nevada
It was difficult for Hannibal due to the idea of doing it during winter and with elephants. For Caesar, it would be as hard as it is for militias in the Egypt's Sinaï today. Aka, pretty easy. For years, Egypt has failed to secure the mountains of Sinaï, despite their modern army and the fact that the Sinaï is right next to them. Because none can really "secure" a mountain, or prevent infantry movements there. Even a modern army has trouble doing it (the Talibans can still move around in the mountains pretty easily, despite our drones)
And moving the bulk of his army through the mountains would leave Caesar open to a counter-attack by the NCR on his own supply lines while he's bogged down in the mountains.
True, but then again, I really don't think he'd even need to go for Shady Sands.
We don't know about the Shi. They're not even mentioned in New Vegas, which suggests to me they no longer exist (as if they were still around, they'd merit a mention at least). I reckon absorbed into the NCR. In any case, they're intelligent folk. They're not going to be stupid enough to side with Caesar. Either they don't know him, and they're too clever to side with a complete unknown
Their emperor-calculator did calculate the probability of military risks in Fallout 2, taking account of the NCR forces. Should the NCR face a Legion invasion and lose the Hub, no doubt that the Shis could easily calculate the odds, and take a pragmatic decision. They'd probably stay as neutral as possible for a while, until taking a side.
If they still exist, that is. I thought I read that they became an independent faction, but I was wrong about that. If anything, they were probably assimilated by the NCR, that's true.