The brooch depicts what is called Blood China or Blood Chit, the closest translation being blood pact or blood piece. In practice, the military (especially pilots) allied with the Chinese sewed on their jackets or wore a scarf, a parchment, a sign of recognition with the designs of the allied flag and the text written in Chinese and sometimes more languages so that if they were shot down or they fell into enemy territory and could, with this symbol, be assisted by Chinese soldiers or civilians, a sort of identification passport. This symbol was mostly used in World War II especially by Americans and British