I only found this video because Piers Morgan from CNN tweeted it. Very moving. The Defence Force explain at You Tube:
Haka is used throughout New Zealand by many, not only Māori, to demonstrate their collective thoughts. There is a haka for each of the Services, as well as the Defence Force. Units with the NZ Army have their own haka. This video shows the soldiers of 2/1 RNZIR Battalion performing their Unit haka, powerfully acknowledging the lives and feats of their fallen comrades as they come onto the Unit’s parade ground. It is also an emotive farewell for they will leave via the waharoa (the carved entrance way) for the very last time.
Haka –sometimes termed a posture dance could also be described as a chant with actions. There are various forms of haka; some with weapons some without, some have set actions others may be ‘free style.’ Haka is used by Māori (indigenous people of New Zealand) for a myriad of reasons; to challenge or express defiance or contempt, to demonstrate approval or appreciation, to encourage or to discourage, to acknowledge feats and achievements, to welcome, to farewell, as an expression of pride, happiness or sorrow. There is almost no inappropriate occasion for haka; it is an outward display of inner thoughts and emotions. Within the context of an occasion it is abundantly clear which emotion is being expressed.
They will not be forgotten.