The great Maori warriors of old would have a pre-battle ritual, the Haka. It was a combination dance and chant intended to both psych up their own side and intimidate the other side. The Maori swept the South Seas islands clean of opposition, in part because of this.
The ritual continues to this day, with the New Zealand All Blacks rugby team, likely the best rugby team on the planet. Pretty amazing when you consider that there are twice as many people in the Atlanta metropolitan area as in the entirety of New Zealand. But if Atlanta has a rugby team, I haven't heard of it.
This is a great example of a Haka, not just because it's typical for the All Blacks, but because they were playing Fiji who led the ceremony off with their own version, the Cibi. Imagine a battlefield in days of yore, with a thousand warriors on each side doing this before picking up lethal weapons. The hair on the back of my neck stands up watching this.
This is a more extended Haka which really highlights the intimidation factor.
To this day the Kiwi Armed Forces welcome back their fallen brothers with a ceremonial Haka.