Olympia: The Age of Gods PBEM (Jul 10 2001)
When a unit is attacked, it may call in allies to help defend itself.
In particular, when a unit is attacked, all other units in the same
location who have placed that unit on their defend
list will join
on the defending unit's side in the battle. In addition, if the unit
being attacked is in a sublocation (such as a castle), allies in the
outer location will also join in the defense.
However, since allied units are usually responding to the news of the attack from some distance away, they do not join the battle until the beginning of the second round. If the defender is defeated in the first round the battle will end immediately, before any allies have a chance to come to his aid.
For more on the defend
list, see Declared attitudes.