Breakdown of the Jin–Song Alliance

Timeline

1. 1125Huisheng Prefecture, the Jin capital · HeilongjiangAfter Liao's fall, Emperor Taizong of Jin decided to tear up the Alliance on the Sea and prepare war against Song, citing Song's failure to honor the alliance and its unauthorized occupation of parts of the sixteen prefectures of Yan and Yun.
2. 1125Yanshan · HebeiZonghan, Zongwang, and other Jin commanders advanced south in separate columns, crossing the Yanshan defense line into Song territory; the Jin and Song formally went to war, and the Alliance on the Sea existed in name only.