The first sign of the deterioration of Sun Quan's reign occurs in 230, when he sends his generals Wei Wen and Zhuge Zhi with a navy of ten thousand into the East China Sea to seek the legendary islands of Yizhou and Danzhou to seek to conquer them, despite the strenuous opposition of Lu Xun and Quan Cong.

The Wu navy is not able to locate Danzhou but locates Yizhou (Taiwan), and returns in 231 after capturing several thousand men—but only after eighty to ninety percent of the navy has died from illness.

Instead of seeing his own fault in this venture, Sun Quan simply executes Wei Wen and Zhuge Zhi.