Shields + spears and trained in formation, I would say they would do pretty well.
I always thought that it made no sense in all these zombie movies they would not use spears. Just build barricades, leave enough space for you spear to go through and go to town. Easy game.
All classic zombie fiction relies on people being unfamiliar with zombies.
Zombie Survival Guide acts as a manual on how you’d deal with an outbreak, and it pretty much says any organized human group would just systematically exterminate them. World War Z, novel based on the same rules, depicts humans returning to formation warfare tactics (except with bayoneted marksman rifles). A battle between the army and zombies resembles a cattle roundup with shooting more than it does a “battle,” and when the reforms are made the army’s casualty rate plummets to zero. The only dangerous jobs are urban warfare (due to chances of a crawler or ambush) and underground in tunnels (extremely hazardous).
If it’s a bite —> illness —> die —> come back cycle, keep in mind how quickly modern illnesses spread due to how much people travel around. A people that don’t know to destroy the plane and the slightest contact of fluid on fluid infects you. You can get bitten, go to the hospital with severe illness, reanimate and then bite several more people in the ward. Nobody in your setting can explain what’s going on.
Through the power of exponential growth, you’ve got simultaneous outbreaks going on in dozens of places before anyone notices. Traffic jams form as panic begins and turn into snakes of infection spreading. Collapse of logistics, civil disorder. To an individual, being overrun/trapped is the danger. A rural town is unlikely to be swallowed whole by its own infection, but a city would, like by its own gravity, get sucked under.
Realistically you wouldn’t get an apocalypse (they don’t in World War Z). But you absolutely could have mass death and chaos for years. If your setting throws in non-bite vectors of contagion (like it spreading in the water/air, by rodents or insects, supernaturally), even worse. Make the zombies fast and have basic tool use/problem solving (like working a knob) and it’s extremely dangerous.