Was the Mexica war cry ‘atl tlachinolli’?

You’re referring to the Mexica metaphor for war, atl tlachinolli, roughly translatable as water-and-fire. This question has come up before and we’ve not been able to give a full answer (follows links below). Now we’ve benefitted from corresponding with one of our longstanding Panel of Experts members, Professor Stephanie Wood, who has kindly given us some useful leads to follow. Even so, evidence for specific Mexica war cries is VERY scanty!
Prof Wood’s first point is perhaps the most immediately relevant to your question: she points out that ‘the atl tlachinolli often took the form of speech scrolls, and therefore could have a war cry association.’ What’s more, the two animals most often shown ‘voicing’ the war symbol - the jaguar and the eagle (pic 1) - were strongly linked to Aztec warriors.

Pic 1: Depictions of a jaguar warrior voicing ‘atl tlachiinolli’ (Aztec wooden war drum from Malinalco, L); an eagle ditto - drawing based on an Aztec foundation stone monument, Museo Nacional de Antropología, Mexico City (R)

Interestingly, though, other creatures in the Aztec world had associations with war cries. Take the mysterious ahuitzotl (water dog) (pic 3) - ‘a mammal whose back and tail are made of water; on the end of its tail there is a tiny human hand. This figure typically appears as sculpture, both in relief and in the round, but is shown in codices as well. These creatures are dangerous, as they can pull people into the water - with that little hand - and drown them. They also let out war cries...’ (de la Fuente 2004: 48-49). Look at the sculpture in picture 3: could that be the atl tlachinolli symbol again - below its mouth? And did you spot the little human hand in the creature’s tail?
We’re left with the question of exactly what did these ‘war cries’ consist of? As practitioners of Nahuatl (Aztec) chanting in schools in England, we somehow have doubts about whether Mexica warriors would actually have chanted Atl tlachinolli! - it doesn’t exactly lend itself to a rhythmical chant, in the way that, for example, the name of the sun god Tonatiuh certainly does. We suspect that atl tlachinolli was used as a verbal and visual symbol for war, and that the cries emitted by warriors about to do battle would likely have been fierce animal-like shouts, growls, grunts and other atavistic (primeval) calls. But we don’t know for sure...!

Pic 3: Stone sculpture of an ahuítzotl (Aztec water dog), Museo Nacional de Antropología, Mexico City