Dù Yù 杜預
Style name Yuánkǎi 元凱; enfeoffed as Marquis of Dāngyáng 當陽侯. Native of Dùlíng 杜陵 in Jīngzhào 京兆 (modern Xī’ān). Grandson of the Wèi general Dù Jī 杜畿. Married Sīmǎ Yì 司馬懿’s youngest daughter, the Princess Gāolù 高陸公主, and rose under the early Western Jìn through both the Sīmǎ family connection and his own administrative competence to the position of Generalissimo Conqueror-of-the-South (Zhènnán dà jiāngjūn 鎮南大將軍). He was the principal commander of the southern wing in the 280 conquest of Wú 吳 that reunified the empire under the Jìn 晉, for which he was elevated and given the marquisate.
In retirement after the conquest, Dù devoted himself to the Zuǒzhuàn, declaring (in the often-cited remark recorded in the Jìn shū) that he had “Zuǒzhuàn mania” (Zuǒ chuán bì 左傳癖). His Chūnqiū jīng zhuàn jí jiě 春秋經傳集解 (KR1e0002) — completed before his death and presented to the throne posthumously — is the foundational extant commentary on the Zuǒzhuàn and the work that fixed the now-canonical layout in which each Chūnqiū annal is interleaved with the corresponding Zuǒzhuàn narrative. He also produced the Chūnqiū shì lì 春秋釋例 (KR1e0012), a separately circulating handbook of his “fifty fán” 五十凡 (general principles) plus the Chūnqiū place-names; survives only in the SKQS reconstruction from Yǒnglè dàdiǎn 永樂大典 fragments.
Dù was also a polymath in mathematics, hydraulics, and military engineering: he is credited with designing the famous yellow-river bridge at Mèngjīn 孟津, with introducing systematic flood-control measures, and with a calendrical reform based on the Tài shǐ 太始 system. The Jìn shū gives him a substantial liè zhuàn biography (juan 34). He is canonized in the Wén miào 文廟 as one of the patrons of Chūnqiū learning, and his Jí jiě underlies the Táng zhèngyì of Kǒng Yǐngdá (KR1e0003 / KR1e0004) as well as every subsequent Zuǒzhuàn edition into the modern critical tradition (Yáng Bójùn 1990).