因公

in the course of doing one's work / on business

old variant of 因[yin1]

cause / reason / because

public / collectively owned / common / international (e.g. high seas, metric system, calendar) / make public / fair / just / Duke, highest of five orders of nobility 五等爵位[wu3 deng3 jue2 wei4] / honorable (gentlemen) / father-in-law / male (animal)

to die in the course of performing one's duty (idiom)