Though I’m not into numerology, it did give me pause to realize that one of the key moments in the founding of the Ming Dynasty occurred exactly 666 years ago.

On the second day in the sixth month of an Yiwei year that corresponds to the Western date of July 10, 1355, Zhu Yuanzhang led his newly-acquired fleet from Hezhou, his temporary base on the northwest bank of the Yangzi River. He was headed toward a outcrop on the far shore known as Ox Barrier. One of Zhu’s newest recruits, Chang Yuchun, was the first to make landfall. Chang jumped to the shore, wielded his ax and rushed toward the Mongol troops. Zhu Yuanzhang’s Red Turbans surged behind Chang’s charge and routed the imperial army from their fort in the cliffs. Chang’s attack was so heroic that it is said you can still see his footprint in the boulders above the site of the landfall.

Such are the tall tales told of that fateful moment.

I consider this river crossing to be such an important date because it marks when Zhu Yuanzhang emerged as a military leader in his own right. Born a peasant in rural Anhui Province, he served in a Buddhist temple for several years before joining the Red Turban uprising in 1351. Zhu fought under the banners of a local bravo known as Guo Zixing, who recognized Zhu’s talent, married him into his household, and began promoting him among the ranks. It was a difficult relationship in a tempestuous era, but Zhu did not waver in his support of Guo until Guo’s death in early 1355. Then all bets were off and the entire Guo clan was dead by the end of the year, save a girl who was either Guo Zixing’s daughter or granddaughter, and later became the mother to five of Zhu Yuanzhang’s many children.

Taking an army across the Yangzi was no small matter. Zhu Yuanzhang had no boats and had never even seen the Yangzi when he first began to contemplate crossing China’s longest river to set up a base in the city we now call Nanjing. The advisors around Zhu filled his head with the idea of leaving the poverty and suffering of the Huai River Valley for the wealth and comfort of the south. They told him that Nanjing was a place where the dragon coiled and the tiger crouched – an ancient capital where a hidden talent could emerge as a conqueror.

This idea proved irresistible. So even as he was grieving the death of his mentor, Guo Zixing, Zhu was also meeting with a band of boat families feeling hemmed in and oppressed in Lake Chao. They needed to escape, they needed protection, and they had boats. A lot of boats.

This was the fleet that carried Zhu Yuanzhang’s soldiers across the Yangzi. It still took several years for Zhu to found the Ming Dynasty in 1368. However, this breakthrough moment is what put Zhu on the national stage. It was one of what I consider the three key dates that led to the Ming: the others being 1344, when Zhu lost his family to the plague and was forced off his life trajectory; and 1363, when he defeated Chen Youliang in the most significant battle of fourteenth-century China.

The story of the Yangzi crossing is also the subject of my latest novel, which I am writing now, sitting at my desk with a glass of wine wondering what it was like to cross that churning river in 1355, a devilish 666 years ago today.