Moses' assumption, however, that Sihon should permit Israel to pass through sounded in Sihon's ears like a summons to the keeper of a vineyard to permit one to harvest it. Sihon's answer therefore was as follows: "I and my brother Og receive tribute from all the other Canaanite kings to keep off their enemies from access to the land, and now you ask me to give you free access to Canaan!"
War between Sihon and Moses ensued, and ended in a brilliant victory for Israel. Sihon and his son, who equaled him in heroic strength, found their death in this fray. God had so brought it to pass that Israel had no need of laboriously waging war upon one city after another in Sihon's land, He had brought all the hosts of this Amorite king together into Heshbon.
They might without compunction keep the former provinces of Moab and Ammon because they took them not from these, but from Sihon and Og, who had captured them. At this time the king of Moab was Balak, who was formerly a vassal of Sihon, and in that capacity was known as Zur. After Sihon's death he was chosen king, though he was not worthy of a rank so high.
Heshbon, Sihon's capital city, had formerly belonged to Moab; but the Amorites, thanks to Balaam and his father Beor's support, had taken from Moab these and some other regions. The Amorites had hired these two sorcerers to curse Moab, with the result that the Moabites were miserably defeated in the war against Sihon. "Woe to thee, Moab! Thou art undone, O people of Chemosh!"
When this city therefore and the hosts within it were destroyed, all the rest of Sihon's land lay open before them. Israel's victory was all the more marvelous, because Heshbon was an exceptionally well fortified city, so that, had gnats been its inhabitants, it could not have been captured by mortal means, much less so when manned by the hero Sihon and his heroic warriors.
Moses was sorely afraid of waging war against this giant, but God put Sihon's and Og's guardian angels in chains, and then said to Moses: "Behold, I have begun to deliver up Sihon and his land before thee: begin to possess, that thou mayest inherit his land."
These and similar utterances were the ominous words that Balaam and his father employed against Moab. Chemosh was a black stone in the form of a woman, that the Moabites worshipped as their god. As part of Moab passed into Sihon's possession so did a part of Ammon fall into Og's hands, and because Israel had appropriated these land, the Moabites feared they would filch from them all their land.