In 628 BCE, Duke Wen of Jin had just died, and before his funeral could be held, the state of Qin seized the opportunity to attack Jin, destroying the border city of Hua. When the crown prince of Jin heard the news, he erupted in fury, declaring, "Qin dares to attack our city while we are in mourning!" He then mobilized troops to ambush the Qin army at the Xiao Mountains. The Qin forces suffered a catastrophic defeat, with not a single soldier escaping; even the three main generals, including Meng Mingshi, were captured. They were only able to return to Qin thanks to the intervention of Duke Wen's wife, who was also Duke Mu of Qin's daughter.
Three years later, Duke Mu of Qin sent Meng Mingshi and his army to attack the state of Jin. After crossing the Maojin Ferry by boat, Meng Mingshi ordered all the ships burned to the ground, vowing to fight to the death and avenge their total defeat three years prior. United by a shared hatred, the Qin forces crushed the Jin army, capturing the cities of Wangguan and Hao, and terrifying the Jin soldiers into staying behind their walls, too afraid to engage in open battle.
The Qin army emerged victorious and crossed back over the river at Maojin Pass. Arriving at Yao, they buried the remains of their soldiers who had died in battle three years prior and held a funeral for the fallen. Duke Mu of Qin personally conducted the memorial rites, weeping for three days and three nights.
To cross the river means to ford it. The idiom "Burn the Boats After Crossing the River" means to burn the boats after crossing, cutting off all retreat and fighting to the death, describing high morale and courageous combat.
Source: *Records of the Grand Historian*, "Basic Annals of Qin"
Meaning of the Idiom: Later, the Chinese idiom "济河焚舟" came to describe how to burn the boats after crossing, cutting off all retreat and fighting to the death, describing high morale and courageous combat.