Alliance Conducted at Sea

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Overview
The Alliance Conducted at Sea was a 12th‑century political pact between the Song and Jin dynasties of China against the Khitan‑led Liao dynasty. It was negotiated from 1115 to 1123 by envoys crossing the Bohai Sea. The two sides agreed to invade Liao together, split the lands they captured, transfer the Sixteen Prefectures to the Song, and avoid making separate peace with Liao.

Background
In 1005, Song and Liao signed the Chanyuan Treaty, which ended large‑scale conflict and meant Song officially conceded the loss of the Sixteen Prefectures. Peace followed for decades. The Alliance was formed to overturn this arrangement: if successful, the Song would stop receiving annual payments from Liao and instead receive support from Jin, while Jin would obtain the Sixteen Prefectures from Liao.

What happened
Invasions were carried out jointly, and by 1125 the Jin were able to force the Liao court to flee toward Central Asia, where it formed the Western Liao dynasty. Jin handed over several of the Sixteen Prefectures to the Song, including what is today Beijing. However, the alliance collapsed in 1125 as the Jin perceived Song weakness, and the overall campaign did not go as planned. In 1127, Jin forces captured the Song capital Kaifeng, marking the end of the Northern Song dynasty.

Aftermath
The Humiliation of Jingkang occurred when the Jin captured Emperor Qinzong and Emperor Huizong and sacked Kaifeng. The Song court fled south and established the Southern Song dynasty. The alliance thus ended with a decisive shift in power in northern China.

See also
- Jin–Song Wars
- Treaty of Shaoxing
- History of the Song dynasty
- Timeline of the Jin–Song Wars
- History of Beijing