Replacements: "fired upon"

[raizer]

Any fire, regardless of effect will prevent replacements going to a unit that was fired upon-same with fatigue recovery.

Arty on an entire stack will only prevent replacements if you have the alternate artillery resolution because, with that rule, every unit in the hex is affected by the artillery. If you are using "normal" artillery fire rules, where you have to target each unit you are shooting at, the automatic defensive fire done by the AI will prevent replacements from each individual unit that is attacked by artillery.