I'm presuming that intelligence about the exact location of targets in a ruin is going to be far less precise and starvation and privation are going to start killing faster than bombs. Ironically the armed gang will probably weather than particular challenge than the general population. Incremental improvements in number of combatants dead is going to come at the expense of a much larger contingent of dead civilians.

Hamas was I believe said to have what 50,000–60,000 fighters. By the time they get to the halfway point half the population will be dead.