Why is the Battle of Ap Bac considered perhaps the most important confrontation of the entire Vietnam War?

The Battle of Ap Bac is viewed as an important battle in the Vietnam War for the following reasons. The victor of the battle is not clear. While the VC are eventually forced to flee, the ARVN forces are vastly superior and should have routed them very quickly. The ineptitude displayed in this battle is great propaganda fodder for the VC.