@crsluggo Hi crsluggo,
When British Commandos are supported by artillery in an attack, they attack at “3” - and the artillery at “2” as usual.
After the attack, any surviving Commandos operate under regular infantry rules - but they are still Commandos.
So, during any future attack they (again) attack at “3” - when supported by artillery. Otherwise they attack at “1” as regular infantry - even though they are Commandos.
In other words; the artillery unit is the key.
The same rule applies to US Marines.
Please note: German Waffen-SS infantry units have similar qualities when supported by Waffen-SS Artillery.