 Song armies led by general Bi <unk> ( <unk> ; d . 1217 ) captured the barely defended border city of <unk> <unk> ( on the north bank of the Huai River across from modern <unk> County ) but suffered large losses against the Jurchens in Hebei . The Jin repelled the Song and moved south to <unk> the Song town of <unk> <unk> on the Grand Canal just south of the Huai River . Bi defended the town , and the Jurchens withdrew from the siege after three months . By the fall of 1206 , however , the Jurchens had captured multiple towns and military bases . The Jin initiated an offensive against Song prefectures in the central front of the war , capturing <unk> and <unk> ( <unk> ; on the Han River near modern <unk> ) . By the fall of 1206 , the Song offensive had already failed <unk> . Soldier morale sank as weather conditions worsened , supplies ran out , and hunger spread , forcing many to desert . The massive <unk> of Han Chinese in northern China that the Song had expected never materialized . 
