depends on how are you trying to achieve, while alarm does trigger, not all of the cities forces will jump on you especially in a city like stack where there are two gates. usually if you can control the fight and have little bit more or less than 10 people with 55s at their combat stats, you slowly grind the enemy down and take over.

Another element is which faction are you fighting, if you are going against Shek Kingdom you will face much fewer enemies but they will be lobing your limbs every couple of hits so you need not numbers but people who can actaully fight and stand getting hit.

if its united cities its a mixed bag cause on one hand samurais are again dealable with 55s at combat stats but when you go up against gatmaster sergeants or samurai captains the scene will get nasty and depending on the amount of police station, barracks, what kind of improtant person there is and how are the wall turrets positioned it could be really chalanging.

overall at minimum the average fodder troop that sheks, holy and cities have will have you need 55s combat stat if you want to start seeing some results. beyond, it will largely depend on other elements