Bonhams' third Asia Week sale - the Xi'an Incident: The Papers of Hyland "Bud" Lyon - took place on March 20, and boasted a number of high-selling, historical documents relating to the 1936 event.
The 1936 coup saw nationalist Chinese general Zhang Xueliang force military leader Chiang Kai-shek into house arrest in the city of Xi'an.
The imposition impelled Chiang Kai-shek to negotiate with the communist leader, Mao Zedong, in the hope of bringing an end to hostilities between the two sides, and enabling them to focus their attention on the invading Japanese army.
An informal agreement was achieved a fortnight later, allowing Chiang Kai-shek to leave his home.
Subsequently, Zhang Xueliang, fearing for his safety, hired a bodyguard. Hyland "Bud" Lyon, a former Hollywood stuntman, filled the position, becoming Xueliang's personal pilot and confidant.
Director of fine books and manuscripts at Bonhams', Dr Catherine Williamson, comments: "There will never be another auction quite like this. I am thrilled with the results."
The top lot of the $2.7m auction was a manuscript written by Zhang Xueliang on January 6, 1936, which betrays intensely personal and patriotic feelings. It sold for $854,500, testament to its unusual and telling contents, as well as the strength of the market for Asian collectibles more generally.
Two peace agreements signed by Mao Zedong also put in a strong performance, bringing $506,500, while an extensive collection of Lyon's personal correspondence and photographs sold for $482,500.
Asian collectibles are hot property among investors, as the recent $3.4m sale of a Qianlong emperor's seal underlines.
For auction insights direct to your inbox, sign up for our free weekly newsletter.