Axis & Allies is unusual for a wargame in that combat lasts an indefinite number of rounds. Realistically, attacks often ran out of time or supplies. Some possible rules are:
- 1 round only
- Up to 3 rounds
- Combat ends if no one hits during a round
If the battle ends with both sides intact, there are number of reasonable ways to handle things.
- The attacker must retreat
- The side that has lost the most units must retreat. Defender wins ties.
- The side that has the fewest units left must retreat. Defender wins ties.
- Both sides remain. Units in contested areas can't move into enemy-occupied/controlled areas
Different rules could be used for land or sea battles. For realism, land combat could be limited to 3 rounds, with the units remaining in the area, while sea battles could be 1 round, with side suffering the most losses retreating.
AA14 limits ground combat to 1 round.