An arrogant army inevitably must be defeated
Refers to the defeat that must inevitably come when underestimating one's enemy
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古人说:“骄兵必败”。这正是曹操赤壁失利的根本原因 | Gǔrén shuō: “Jiāobīngbìbài”. Zhè zhèng shì cáocāo chìbì shīlì de gēnběn yuányīn
In ancient times, people said "pride comes before a fall." This is the root cause of 曹操's (Cáo Cāo) defeat in the battle of 赤壁 (Chì Bì, Red Cliff)
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学习上同样也是骄兵必败 | Xuéxí shàng tóngyàng yěshì jiāobīngbìbài
Being cocky in your studies can lead to failure
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Pride comes before the fall
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The 匈奴 were a massive power on the steppes of East Asia for over 200 years. They were eventually defeated in the Han-Xiongnu War (汉匈战争, Hàn Xiōng Zhàn Zhèng) in the year 89.
车师 (Chē Shī) was a country in what the Hàn Dynasty called the "Western Regions," or the 西域 (Xī Yù). The Yumen Pass (玉门关, Yù Mén Guān) in the modern-day province of 甘肃 (Gān Sù) marked the edge of these regions. You can read more about 车师 here
《汉书》(Hàn Shū), a work documenting the history of the Western Han dynasty (西汉, Xī Hàn, 206 BC - 8 AD). It was written by 班固 (Bān Gù), and is generally known in English as the "Book of Han" or the "History of the Former Han."
During the Western Hàn Dynasty (西汉, 206 BC - 8 AD), the emperor 宣帝 (Xuān Dì) ordered his troops to invade the western country of 车师 (Chē Shī). 车师 was unable to repel the attack, so they requested aid from the 匈奴 (Xiōng Nú) tribe. Unfortunately, the 匈奴 didn't arrive in time, and 车师 had no choice but to surrender to the invading Hàn forces.
After their victory was secured, the Hàn minister 郑吉 (Zhèng Jí) garrisoned three hundred soldiers in their new territory, and then he led the rest of the troops on their return journey.
Soon, though, the 匈奴 forces launched an attack on the garrisoned Hàn troops. 郑吉's forces attempted to save them, but they quickly found themselves outnumbered, and 郑吉 rapidly dispatched a message to the emperor requesting aid.
Back in the capital, the emperor called together his advisors to determine how to proceed. There were two leading suggestions. The first came from general 赵充国 (Zhào Chōng Guó), who advised that they take advantage of the 匈奴's overall weakness and invade the tribe as a whole. The second came from the prime minister (丞相, chéng xiàng) 魏相 (Wèi Xiāng), who advocated only rescuing the besieged troops. He told the emperor, "The 匈奴 haven't invaded us over these past few years, and it doesn't make sense to invade them over the country of 车师. The lives of our people on the borders is very rough, and they often find themselves without clothing or food, so how could we happily jump into a war? Even if we did, and we beat the 匈奴, we would have a bigger issue on our hands: our army would become one that depends on its country's might and large population, and an army that does this becomes an arrogant army — and an arrogant army always loses."
The emperor heeded his prime minister's suggestion, only sending enough troops to bring back 郑吉 and his besieged soldiers.