atl tlachinolli.

Headword: 
atl tlachinolli.
Principal English Translation: 

flood and scorched earth, a metaphor for battle or war (see Molina)

Alonso de Molina: 

atl, tlachinolli. batalla o guerra. metaphora.
Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 8v. col. 2. Thanks to Joe Campbell for providing the transcription.

Attestations from sources in English: 

tlachinolli teoatl = [scenes of] war (early seventeenth century, central New Spain)
"atl tlachnolli (water and scorched fields)...traditional metaphor for battle or war."
Annals of His Time: Don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, James Lockhart, Susan Schroeder, and Doris Namala, eds. and transl. (Stanford: Stanford University Press, 2006), 48–49.

in yaoc in moteneva in teoatl in tlachinolli = in battle, in what is called the flood, the conflagration (central Mexico, sixteenth century)
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 235.

In teoatl in tlachinolli: This was the standard metaphoric couplet for war ( see Seler 1902—1923, III: 221—304; Quiñones Keber 1989a). (central Mexico, sixteenth century)
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 235.

auh ac colinjz ac qujiolitiz in vevetl, in aiacachtli, in vncan molnamjquj, in vncan moiocoia in teuatl, in tlachinolli = And who will move, who will put life into the drum, the gourd rattle where war is recalled (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 6 -- Rhetoric and Moral Philosophy, No. 14, Part 7, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1961), 23.

ca itechpa mjtoaia, tepan qujtlaça yn xiuhcoatl, in mamalhoaztli, q. n. iaoiutl, teuatl, tlachinolli. Auh yn jquac ilhujqujxtiloia, malmjcoaia, tlaaltilmjcoaia: tealtiaia, yn pochteca. = For it was said of him that he brought hunger and plague—that is, war. And when a feast was celebrated [for him], captives were slain; ceremonially bathed slaves were offered up. The merchants bathed them. (central Mexico, sixteenth century)
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 1 -- The Gods; No. 14, Part 2, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1950), 1.