In the late Spring and Autumn period, Wu's power swelled, and King Fuchai of Wu, eager to become the hegemon of the Central Plains, led an army to Huangchi (southwest of present-day Fengqiu, Henan) in 482 BCE, summoning all lords to a covenant where he would be declared leader. To showcase his might, Fuchai overnight divided his 30,000 troops into three armies—left, center, and right—each arranged in a square formation of a hundred rows with a hundred men per row. He personally raised a battle-axe, with bear and tiger banners, commanding the center army forward. The entire center force wore white robes, white armor, white flags, and white arrow feathers, looking like a vast field of white blossoms; the left army of 10,000, all in red robes, red armor, red flags, and red arrows, blazed like a raging fire; the right army, clad in black, loomed like a dark cloud.
The three armies marched to the alliance site and formed their ranks. As dawn broke, King Fuchai of Wu personally sounded the drums and gave the order; thirty thousand soldiers roared in unison, their cries shaking heaven and earth, startling all the assembled feudal lords.
With the Wu army's formation so grand and its martial might so imposing, the feudal lords dared not contend with King Fuchai of Wu and were compelled to acknowledge him as their hegemon. At the Assembly of Huangchi, after King Fuchai displayed his army's magnificent and overwhelming presence—"blazing like fire and spreading like thatch"—the gathering achieved its success.
The idiom "Ru Huo Ru Tu" means as red as fire and as white as reeds, used to describe a grand military array. Now it often signifies great momentum.
Source: *Guoyu*, "Discourses of Wu"
Meaning of the Idiom: Later, the Chinese idiom "如火如荼" came to describe as red as fire and as white as reeds, a grand military array. Now it often signifies great momentum.