his reputation, turning the tide of the battle. In the Battle of Bi, 597 BC, the routing chariot forces of Jin were bogged down in mud, but pursuing enemy troops stopped to help them get dislodged and allowed them to escape. During the Spring and Autumn period (771–479 BC), Duke Xiang of Song, when being advised to attack enemy Chu forces while the enemy army was fording a river, refused and waited for the Chu army to form formation. After Xiang lost the battle and was being rebuked by his ministers of war, he responded: "The gentleman does not inflict a second wound, nor does he capture those with gray hair. On campaigns, the ancients did not obstruct those in a narrow pass. Even though I am but the remnant of a destroyed state, I will not drum an attack when the other side has not yet drawn up its ranks." His minister retorted, "My lord does not know battle. If the mighty enemy is in a defile or with his ranks not drawn up, this is Heaven assisting us", signifying that by the Spring and Autumn period such attitudes on chivalric honor was dying out. Under the Shang and Zhou, these armies were able to expand China's territory and influence from a narrow part of the Yellow River valley to all of the North China plain. Equipped with bronze weapons, bows, and armor, these armies won victories against the sedentary Dongyi to the East and South, which were the main direction of expansion, as well as defending the western border against the nomadic incursions of the Xirong. However, after the collapse of the Zhou dynasty in 771 BC when the Xirong captured its capital Haojing, China collapsed into a plethora of small states, who warred frequently with each other. The competition between these states would eventually produce the professional armies that marked the Imperial Era of China. Prehistory and Shang dynasty Early Bronze Age Chinese cities were characterised by massive defensive walls. The Erlitou culture's bronze workshops probably gave it a decisive edge over competing groups. Armies were probably relatively ineffective given the prevalence of extensive fortifications, although the Erlitou culture probably succeeded in breaching these occasionally since they were able to expand the area of their control. Starting from the 3rd Millennium BC and throughout the 2nd Millennium BC, there is a correlation between elite status and military