might is right; history is written by the victors
Proverb meaning that the winner is always considered the legitimate side, regardless of the actual justice of their cause. Abbreviation of the longer proverb 勝てば官軍、負ければ賊軍.
See also: 勝てば官軍、負ければ賊軍
勝てば官軍というように、勝った側が正義とされることが多い。
As the saying goes, 'might is right,' and the winning side is often considered just.