In the first version of the Alterac Valley, there was no such thing as reinforcements.
In that version, the deciding factor for victory was not tactics, but the number of people. Because there was no concept of reinforcements, the entire battlefield of Mount Olympus was likely to fight from day to night. At that time, there was no concept of cross-server battlefields. For those servers with unbalanced factions, the victory was decided when one side did not have enough people in the middle of the night.
In the later versions, Alterac Valley underwent a series of changes, mainly in two aspects:
The first was that the various complex mechanisms had been comprehensively weakened, including the removal of most neutral NPCs, the weakening of the guards 'attributes, and the disappearance of many powerful summonable NPCs.
The second was to add the concept of reinforcements, so that the duration of each battle was controlled.