The presence of the Amorites on the eastern side of Jordan is accounted for in a passage extending from vv. 26-30. Moab had apparently, as at a later time referred to by one of the prophets, been at ease, resting securely behind her mountain rampart. Suddenly the Amorite warriors, crossing the ford of Jordan and pressing up the defile, had attacked and taken Heshbon; and with the loss of that fortress Moab was practically defenceless. Field by field the old inhabitants had been driven back, out into the desert, southward beyond the Arnon. Even as far as Ar itself the victors had carried fire and sword. Retiring, they left all south of the Arnon to the Moabites, and themselves occupied the country from Arnon to Jabbok, a stretch of sixty miles. The song of vv. 27-30 commemorates this ancient war:--
"Come ye to Heshbon, Let the city of Sihon be built and established; For a fire is gone out of Heshbon, A flame from the city of Sihon: It hath devoured Ar of Moab, The Lords of the High Places of Arnon. Woe to thee, Moab! Thou art undone, O people of Chemosh."
The chant rejoicing over the defeated goes on to tell how the sons of Moab fled, and her daughters were taken captive; how the arms of the Amorite were victorious from Heshbon to Dibon, over Nophah and Medeba. The Israelites arriving soon after this sanguinary conflict, found the conquered region immediately beyond the Arnon open to their advance. The Amorites had not yet occupied the whole of the land; their power was concentrated about Heshbon, which according to the song had been rebuilt.
The request made of Sihon to allow the passage of a people on its way to Jordan and the country beyond came possibly at a time when the Amorites were scarcely prepared for resistance. They had been successful, but their forces were insufficient for the large district they had taken, larger considerably than that on the other side of Jordan from which they had migrated. In the circumstances Sihon would not grant the request. These Israelites were bent on establishing themselves as rivals: the answer accordingly was a refusal, and war began. Refreshed by the spoil of the fields of Arnon, and now almost within sight of Canaan, the Hebrew fighting men were full of ardour. The conflict was sharp and decisive. Apparently in a single battle the power of Sihon was broken. Leaving his fortress the Amorite chief had gone out against Israel "into the wilderness"; and at Jahaz the fight went against him. From Arnon to Jabbok his land lay open to the conquerors.
And having once tasted success the warriors of Israel did not sheathe their swords. The fortress of Amman guarded the land of the Ammonites so strongly that it seemed for the time perilous to strike in that direction. Crossing the valley of the Jabbok, however, and leaving the fierce Ammonites unattacked, the Israelites had Bashan before them; a fertile region of innumerable streams, populous, and with many strongholds and cities. There was hesitation for a time, but the oracle of Jehovah reassured the army. Og the king of Bashan waited the attack at Edrei in the north of his kingdom, about forty miles east from the Sea of Galilee. Israel was again victorious. The king of Bashan, his sons, and his army were cut to pieces.
Such was the rapid success the Israelites had in their first campaign, amazing enough, though partly explained by the strifes and wars which had reduced the strength of the peoples they attacked. We must not suppose, however, that though the Amorites and the people of Bashan were defeated, their lands were occupied or could be occupied at once. What had been done was rather in the way of defending the passage of the Jordan than providing a settlement for any of the tribes. When the Reubenites, Gadites, and Manassites came to dwell in those districts east of the Jordan, they had to make good their ground against the old inhabitants who remained.