Control in cities is a bit weird. Cities are divided in building blocks, and each can be occupied by a group of infantry. Infantry occupying a block only takes 30% damage from all sources, and is very hard to spot – but only if it is actually garrisoned in the block!
To garrison a block, right click it with your infantry. In this special state they individual squads will teleport between buildings within the block, avoiding napalm or meeting enemy infantry. Every five seconds, you’ll be able to move to an adjacent block. Be careful to click on the block – accidentally ejecting the infantry into open space and losing the 70% damage reduction for even a second is a death sentence with the high unit concentrations and short ranges of infantry combat.
Note that exposing your infantry is not always avoidable – crossing between road-separated city blocks generally means a second of vulnerability. The orange line marks another position that is impossible to safely cross – although there is no road on the west side, the blocks are too far apart.
Another mistake the blue player in the above screenshot makes is using 4-stacks. I haven’t talked about unit grouping much, but city fighting is one of the few cases where big unit stacks are superior to single groups. A good rule of thumb is to use 3-stacks; 4-stacks as used in the screenshot above are too big and will almost always cause some of the infantry to stay out of the fight.
Many towns are not wide enough to fit more than ten or fifteen units on the frontline. This means that if you’re investing a lot of points, it’s sometimes better to go for special forces and other high-quality units; buying too much line may leave you with too little space to put them in.
As previously said, fire support in deep town is unfeasible. The buildings aren’t decorative, they genuinely force vehicles to maneuver between them, making it hard to keep up with the teleporting infantry. Side shots are easy to score, making even WW2 RPGs deadly. It’s still worth sending cheap transports into napalm infantry to distract them from napalming your own men, but chances are they’ll just get picked off by an escorting RPG squad. This limited vehicle usability makes specialized anti-infantry squads like Spetsnaz and Navy Seals shine.
It’s possible to get into CQC in towns: this is a special state that occurs when two squads occupy the same building, turning the sector border purple. Non-CQC machine guns cannot fire in CQC, nor can many special anti-infantry weapons. I don’t think CQC is a very important factor in town fights because the enemy can always retreat a sector back until you’re forced to fight him at the outer edge of town under fire support, but there are uses to it, mainly for punishing napalm launchers.
Not much to learn here – use anti-infantry specialists and be careful about the slacker squads resulting from too big groups. With correct unit choice cities are mostly won by whoever has more infantry. If outnumbered, retreat to the outer edge so that your fire support can dissuade the enemy from finishing off your infantry.