Moses
Numbers 21:21ESV·traditional attribution

Then Israel sent messengers to Sihon king of the Amorites, saying,

John Calvin Reformed @genevareformer

Numbers 21:21. And Israel sent messengers. The second narration, which I have subjoined from Deuteronomy, is the fuller; nevertheless, a question arises from it, for what reason this embassy was sent to king Sihon, whose kingdom was already devoted to the Israelites: for it seems to be altogether inconsistent to offer conditions of peace when war is decreed.

Matthew Henry Presbyterian @wholebiblehenry

We have here an account of the victories obtained by Israel over Sihon and Og, which must be distinctly considered, not only because they are here distinctly related, but because long afterwards the memorial of them is distinctly celebrated, and they are severally assigned as instances of everlasting mercy.

Commenting on Numbers 21:21-35

John Gill Reformed Baptist @doctorgill

And Israel smote him with the edge of the sword,.... Slew him and his army, entirely routed them, and got a complete victory over them; God giving them up into their hands, who otherwise were a very strong, powerful, and warlike people; see Amo 2:9.