You may be overthinking this one. Let's look at the Gulf War as a contemporary example. The allies deployed 950,000 soldiers against Saddam's 650,000. 292 allied soldiers were killed (half of them by accidents), and up to 35,000 Iraqis were killed. As things go, the trend is towards less deaths due to combat over time owing to technological developments. The 2003 invasion of Iraq saw the US led coalition deploying 380,000 soldiers with 172 deaths. It may not be zero, but considering the numbers involved, it's an incredibly low figure.

Casualties depend on how evenly matched your forces are with your enemy, and how determined they are to fight. This wasn't just a military conflict; the Americans in particular led a propaganda campaign against both the Iraqi soldiers they were about to fight, and their own people. That would be necessary in your case too. It has been said that America's propaganda, inclusive of leaflet drops, were a contributing factor to the surrenders in the Iraqi army.

Another case study worth considering is Operation Cast Lead. This is a good example of the evolution of hardware and tactics to suit urban fighting. And you may like to examine recent innovations from the Israeli defence industry, which are often specifically for circumstances like these. However, in this case (unlike your own) there were many civilians present and killed.

In your situation the fanatic enemies may deliberately cluster around what's left of the civilian population, which causes a lot of problems for even the most sophisticated guided bombs. Modern artillery shells can be guided to within meters of their targets when fired from tens of kilometres away, and so if the enemy forces are nowhere near civilians they can quite safely and accurately be shelled into oblivion at great distance with artillery, aircraft, and missiles.

Perhaps the waiting game is the best option. Allow any civilians safe passage out, hold the perimeter around the city, turn off the water, and wait. At best it'll be a few months until the defenders are dead or too weak to fight. That would depend on your ability to create and hold a perimeter, assuming they no longer have supply lines.

The bottom line is that with patience, overwhelming numbers, and superior technology, you can win with very few casualties.

You may be overthinking this one. Let's look at the Gulf War as a contemporary example. The allies deployed 950,000 soldiers against Saddam's 650,000. 292 allied soldiers were killed (half of them by accidents), and up to 35,000 Iraqis were killed. As things go, the trend is towards less deaths due to combat over time owing to technological developments. The 2003 invasion of Iraq saw the US led coalition deploying 380,000 soldiers with 172 deaths. It may not be zero, but considering the numbers involved, it's an incredibly low figure.

Casualties depend on how evenly matched your forces are with your enemy, and how determined they are to fight. This wasn't just a military conflict; the Americans in particular led a propaganda campaign against both the Iraqi soldiers they were about to fight, and their own people. That would be necessary in your case too. It has been said that America's propaganda, inclusive of leaflet drops, were a contributing factor to the surrenders in the Iraqi army.

Another case study worth considering is Operation Cast Lead. This is a good example of the evolution of hardware and tactics to suit urban fighting. And you may like to examine recent innovations from the Israeli defence industry, which are often specifically for circumstances like these; and sometimes it's the little things; like having a gun which can shoot around corners. However, in this case (unlike your own) there were many civilians present and killed.

In your situation the fanatic enemies may deliberately cluster around what's left of the civilian population, which causes a lot of problems for even the most sophisticated guided bombs. Modern artillery shells can be guided to within meters of their targets when fired from tens of kilometres away, and so if the enemy forces are nowhere near civilians they can quite safely and accurately be shelled into oblivion at great distance with artillery, aircraft, and missiles.

Perhaps the waiting game is the best option. Allow any civilians safe passage out, hold the perimeter around the city, turn off the water, and wait. At best it'll be a few months until the defenders are dead or too weak to fight. If they do try and break the siege they'll be advancing into your traps and defences. That would depend on your ability to create and hold a perimeter, assuming they no longer have supply lines.

The bottom line is that with patience, overwhelming numbers, and superior technology, you can win with very few casualties.