Surrendering

[TheBigRedOne]

As written in the manual:

After assault losses are computed and applied, a determination is made of whether the defending forces retreat. If the combat calculation results in no defender losses, they do not retreat (Note that the actual losses may differ from the combat calculation because of random variation in how the losses applied). Defending forces that have a non-Wrecked Vehicle with them do not retreat. Otherwise, two random Die Rolls are made. If the first Die Roll is less than or equal to the morale value of the defending units or the second Die Rolls greater than the morale value of the attacking units, then the retreat does not occur. Retreating defenders automatically become Demoralized. Crew-served weapons are only retreated if they have sufficient crew to carry them, otherwise they are left in the defending hex.

Demoralized defending units that have no valid way to retreat are eliminated and considered to have surrendered. This does not apply to Japanese units however.

This is still resolved upon assaulting the unit, not just firing upon them. In SB a unit will not simply 'surrender' and leave the screen unless it is assaulted, to my knowledge.