I don’t have much on strategy - but you mentioned AA capabilities. So I’ll point out that the Germans used their 88mm Flak (AA) gun as an effective anti-tank weapon during WWII. You could possibly use this to your advantage - essentially increasing your anti-tank abilities.
No, not a problem here. Maybe - maybe - in the biggest buildings. Maybe daylight basements. Not at all standard, however, at all. The university library is underground, there are underground rooms under the stadiums and such, and there are, say, sunken loading docks, but very few true basements. They’d be flooded.
I’m trying to figure out how to post links to the maps as they change - I want to make it absolutely clear, though, that if I do that I do NOT WANT specific strategic advice for this specific scenario. Research is fine, but getting the Internet to help me actually win the battle is surely cheating.
You say you have to hold the city, but that does not mean you must defend it. By this I mean you should be focused on crippling your enemy rather than keeping what you have.
Keep enough infantry and maybe a few tanks in the city to make taking it slow. Choose a few likely ingress routes to defend heavily. But mostly just leave the city undefended, except for some roving units to scout and harass any inbound enemy.
Use almost all of your tanks and a large number of infantry to do what they do best–attack and destroy enemy formations. Your forces are most effective outside the city, so try to engage the enemy outside the city. Hopefully the enemy will be prepared for urban tactics and not open fields.
If the enemy rapidly pushes into the city, try to flank them and attack their support column. You will be able to destroy his flank outside the city much faster than he can dislodge your troops from their defensive positions inside the city.
Insurgents are a long-term problem. They may be able to disrupt you, no matter what you do, but hopefully its little stuff. Concentrate on the regular enemy for now.
If they’re coming from Fort Jackson, there’s essentially no place that isn’t the city. The fighting is going to be in town one way or another - the farthest out it could possibly be is in-town residential. Don’t picture a city, and then countryside, and then a military base - in every house I’ve ever lived in, if it was a quiet night you could hear reveille. We are already right up on the bastards.
Okay, I’m trying to post the maps and assume they’ll change as they change for us, if anybody’s interested in them. There may be trouble with the permissions, but I’ll give it a go. PLEASE do not reference specific locations or situations - I don’t want to cheat. If you do want to point them out to each other, spoiler box them and I won’t read them.
Infantry dude’s map.
Theater map, including antiaircraft guns and artillery. We don’t control most of this stuff, but we can request support (and the artillery people are supposed to cooperate with me.)
Our intention this turn, considering we only have three orders each per turn and turns are 30 minutes, is to start out fortifying Providence Hospital at the corner of Forest Drive and Millwood and the corner of Devine and Harden. I’ll spread my tanks out to watch the intersection of Millwood and Gervais and Gervais and Harden. He’s also sending infantry and snipers to the stadium on Shop Road. The next turn we’re going to try to do something about Rosewood and make sure we’ve got Gervais under wraps. I’m going to ask the guys with the big guns to pull in past our perimeter or accept the fact that we are not going to be there to help them out. I’m leaving two tanks at our rear by the bridges, just in case of a rear attack, although we don’t consider it very likely.
I am most concerned about missing them altogether and finding them up our asses via Rosewood, but we only have three orders, so whaddaya gonna do?
Combined Arms warfare is like paper-scissors-rock. Armor > Infantry > Anti-tank > Armor .
I have no idea how I missed this thread, but dont use the tanks as a mobile pill box. Keep them together as a mobile response force and use infantry for the trip wires. Set up engagment boxes for the artillery, and if you have engineers , create artificial terrain by urban renewal. If the town is going to be in the midst of a fight, then your orders to keep the place pristine go out the window when the enemy shows up.
Create berms of rubble across natural areas of movement, be they roads or pastures that can handle heavy vehicles, lay land mines.
Regarding insurgents, take your lessons from the boer war and place all the non combatants into concentration camps, anybody else is a target.
Declan
Huh? Seems a tactic likely to get tanks destroyed in an ambush. Set up a meeting engagement between the infantry forces and then when their armor rolls in to rescue their infantry, open up with your pre-plotted artillery and anti-tank weapons and knock out their tanks as they’re out moving in a group.
I don’t think attacking Columbia is a very good idea. They could bring in reinforcements from Harlem and turn Morningside Heights into a death trap for your tanks.
Better attack Penn instead. It’ll be easier going and you can take out some really grungy sections of Philadelphia.
No, still city fighting. If you’re going to attack an Ivy League school, you’re better off attacking Cornell or Princeton. Maybe Dartmouth if you can keep the seniors from getting into the hills and starting an insurgency.
Perhaps not strictly relevent to this thread since the OP has to use the tanks provided, but:
If you had to fight in an urban environment and had your choice of equipment, would some other type of armor- armored cars or APCs- be preferable to main battle tanks? Maybe on a production/maintainence basis you could afford two APCs for one MBT; or maybe gross weight is an issue with regards to bridges, etc. and a smaller vehicle could go where a MBT couldn’t?
If you vill take suggestions under consideration, I have some vile suggestions! 
Do you have/are you allowed to use chemical weapons? If so, what kinds, and how would they be delivered?
How’s Kelly’s Heroes stack up?
Your critical points are the river crossings. Those must be defended at all costs else your army will be cut off. Destroy those you cannot defend like sewers.
As for civilians, you’re Nazis. Kill everyone who isn’t one of yours.
There was an M-113 variant with a 20 mm vulcan for the air defense, I believe has a high elevation , normally for shooting down planes but would do excellent for strafing top floors of buildings that are providing cover for the RPG teams.
Declan