不堪回首 — “Too painful or agonizing to recall”

When Zhao Kuangyin established the Song Dynasty in 960 AD, several other regimes still existed around it. To complete the unification, he successively conquered states like Nanping, Later Shu, and Southern Han, then set his sights on Southern Tang. The ruler of Southern Tang at this time was Li Yu (pronounced 'Yù'), commonly known as Li Houzhu (the Last Ruler Li). Though incompetent in politics and military, he was highly talented in literature and art, excelling in poetry, music, calligraphy, and painting. Having grown up in the deep palace, leading a luxurious life, most of his works depicted scenes of courtly existence.

Li Yu's wife, Queen Zhou Ehuang, was exceptionally beautiful and skilled in painting, calligraphy, singing, and dancing, but unfortunately passed away prematurely. Later, Li Yu fell in love with Ehuang's younger sister, Xiao Zhouhou, and they indulged in drinking and merriment under the flowers and moonlight, completely neglecting state affairs.

The threat from the Song Dynasty grew increasingly severe, but Li Yu remained infatuated with a life of song, dance, and peace, merely seeking immediate comfort and making no preparations for defense, blindly submitting to the Song Dynasty. Whenever the Song Dynasty achieved a military victory or had a joyous occasion, he would immediately send people to offer precious tributes. Later, he even proactively sent a memorial to the Song court, hoping to abolish the Southern Tang state title and become a vassal of Song.

In the autumn of 974 AD, Emperor Taizu Zhao Kuangyin twice dispatched envoys to summon him for an audience in Kaifeng. Fearing Zhao Kuangyin would kill him, Li Yu claimed illness and refused to go. Zhao Kuangyin used this as a pretext and dispatched a hundred thousand troops to conquer Southern Tang. Early the following year, the Song army reached the north bank of the Yangtze River, putting the Southern Tang capital, Jinling, in dire peril. Yet, Li Yu believed the Song army could not cross the Yangtze and spent his days in the palace discussing scriptures with monks and Taoist priests. One day, Li Yu incidentally went out to ascend the city wall and, seeing Song army banners everywhere outside the city, he hastily summoned reinforcements, but it was too late.

By that winter, the Song army had annihilated Southern Tang's last remaining reinforcements and finally breached Jinling. Li Yu was forced to surrender and was escorted to Kaifeng. Dressed in white robes and a gauze cap, Li Yu trembled as he was granted an audience with Zhao Kuangyin. Zhao Kuangyin did not kill him but humiliatingly conferred upon him the title of 'Disobedient Marquis' and settled him within the city. Although nominally a marquis, he actually lived a miserable life akin to a prisoner. Li Yu was a melancholic and sentimental man, and his painful life after surrendering to Song naturally made him utterly depressed.

Soon after, Zhao Kuangyin passed away, and his brother Zhao Kuangyi ascended the throne, known as Emperor Taizong of Song. Taizong revoked Li Yu's title of 'Disobedient Marquis' and conferred upon him the title of 'Duke of Longxi'. However, Taizong was even more suspicious than Taizu. On one occasion, Li Yu expressed regret that he should not have killed two loyal ministers, and when Taizong learned of this, he was extremely displeased. One day, Li Yu composed a ci-poem titled 'Yu Meiren' (The Beautiful Lady Yu). The poem contained lines such as 'Last night the east wind swept through the small pavilion again; my old homeland is unbearable to recall under the bright moon.' The meaning conveyed was that all the beautiful things of the past could no longer be revisited, as recalling them would only bring more pain. This poem reached Taizong, who deeply resented Li Yu for still yearning for his old homeland. Later, several more nostalgic poems reached Taizong, who then sent someone to poison him.