[1] In 225 BCE, a 600,000 strong Qin army led by Wang Ben conquered more than ten cities on the northern border of Chu as a precautionary move to guard the flank from possible attacks from Chu while Qin was invading Wei.
Wang Ben then led his forces north to attack and besiege Daliang, the capital of Wei.
As Daliang was situated at the concourse of the Sui and Ying rivers and the Hong Canal, its geographical location gave it a natural defensive advantage.
Wang Ben came up with the idea of directing the waters from the Yellow River and the Hong Canal to flood Daliang.
Wang Ben's troops worked for three months to redirect the water flow while maintaining the siege on Daliang, and succeeded in their plan.