“A modern mega-city is a tech-construct as vulnerable as a moon-base under a glass dome that runs everything on a nuke plant. Break the dome or shut the plant off and the moon-base or the mega-city will die.”
Vulnerable to whose detriment? How many enemy combatants are there to be destroyed?
A Megacity has a minimum of 10 million residents. And the strength of the enemy combatants will be what, Platoon, Company, Battalion, Brigade, Division, Corps, Field Army?
Let’s say it’s a heavy Corps, 100,000 personnel at the outside (depending on whose Army is at play). That’s one percent of the people in the Megacity. If you take action detrimental to the whole population, the whole Megacity, to get to the one percent, I’d guess that something more than ninety percent are going to try to leave. They may even be forced out by the one percent to save food and water and so on. Something will have to be done with all those refugees, to include vetting them so that no enemy combatants can get through.
Now you can certainly cut electricity. And you can cut food and water to a large extent, but can you cut it completely? Can you cut it enough? I know that in past wars cities have been put under siege till they were conquered, but they weren’t Megacities.
The smallest Megacity is a little over 400 square miles. The largest is over 5000 square miles. That’s a lot of perimeter to secure against the infiltration of supplies. What size force do you have to accomplish this?
And there are undiscussed things like geography (does a river run through it, does it have sea access?). And whose city was it to start with, the enemies, or one of ours that was captured? If it was the enemies, we might not care about the detriment of everyone in it. If it was ours, we might.
Significantly, the objectives of the larger war this action is a part of are undiscussed. If it’s a fight to the finish that’s one thing. If the objectives are more limited that’s something else.
Much of the above has assumed an occupying force of 100,000 in a Megacity of 10,000,000. What if the enemy only occupies part of the Megacity? What if the occupying force is only 10,000 strong?
I believe there are way too many undiscussed variables to dismiss the idea of a Megacities Combat Unit out of hand and just say nuke or besiege the Megacity to the detriment of all within.
I see 100X more downside than upside in trying to fight a Stalingrad or Leningrad today. We are long past throwing 100,000 KIA at a Berlin like the Soviets. It’s long past 1945. I can see a small elite force going in to grab or kill high value targets, but beyond that, it’ll be drones, or it’ll be cutting off the power. You don’t need a 1945 style land force to cut off electricity. You might even accomplish it deniably / false flagged from another continent.
“That’s a lot of perimeter to secure against the infiltration of supplies. What size force do you have to accomplish this?”
Not really. Roads, waterways, railroads, and airways are needed. Controls those and you control supplies.