In ancient times, how did humans overcome their self-preservation instincts to engage in hand-to-hand combat during wars?

Question

In ancient times, how did humans overcome their self-preservation instincts to engage in hand-to-hand combat during wars?

In: 43

Answer 1

Just to add in one factor that I haven’t seen mentioned yet; depending on the culture, they were likely quite drunk and/or a version of high on some sort of plant