This New Zealand Army war cry is actually a farewell to fallen comrades
Like the US military with service and unit mottos, each service and unit within the New Zealand forces has a haka.
From Encyclopedia Britannica:
Haka, (Maori: "dance") Maori posture dance that involves the entire body in vigorous rhythmic movements, which may include swaying, slapping of the chest and thighs, stamping, and gestures of stylized violence. It is accompanied by a chant and, in some cases, by fierce facial expressions meant to intimidate, such as bulging eyes and the sticking out of the tongue. Though often associated with the traditional battle preparations of male warriors, haka may be performed by both men and women, and several varieties of the dance fulfill social functions within Maori culture.
This video shows the soldiers of 2/1 RNZIR Battalion performing their unit haka as a final farewell to their fallen comrades: