Lǐ Déyù 李德裕 (787–850, zì Wénráo 文饒), of Zhàojùn 趙郡 (in fact a Chángān native by long residence), was the dominant chief minister of the Wǔzōng / Huìchāng period (840–846) and the leading figure on the Lǐ side of the NiúLǐ factional struggle that defined late-Táng court politics. Son of the chief minister Lǐ Jífǔ 李吉甫 (758–814), he entered service through the yīn (hereditary) privilege rather than through jìnshì — a fact his political enemies (the Niú faction, identifying themselves with the examination-elite) used against him throughout his career.
His tenures as chief minister: under Mùzōng (821), under Wénzōng briefly, and the dominant tenure under Wǔzōng (840–846). The Huìchāng program included: the suppression of Buddhism (841–845, the Huìchāng fǎnán — closing some 4,600 monasteries and laicizing 260,000 monks and nuns); the campaign against the Uyghur (Huíhú) remnants on the northern frontier; and the resolution of the Liú Zhěn / Zélù military settlement (843–844). At the Xuānzōng succession in 846 he was demoted, then progressively exiled — finally to Yázhōu 崖州 (modern Hǎinán), where he died in 850. His last work, the Qióngchóu zhì 窮愁志 (4 juǎn of historical essays), was composed in Yázhōu exile.
Principal work in the corpus: Huìchāng yīpǐn jí KR4c0067 (20 juǎn zhèngjí + 10 juǎn biéjí + 4 juǎn wàijí); also Cì Liǔshì jiùwén (separately catalogued elsewhere in KR). Catalog gives 787–849; CBDB id 15161 and standard reference works (Jiù Tángshū, Xīn Tángshū) give 787–850, followed here.