Origin
The first known use of ‘might is right’ in the English language was in 1846.
Explanation
The phrase “might is right” refers to the idea that people who have power can do whatever they want. This idea is often phrased a little differently as “might makes right”. In this case, the word “might” is being used in the sense of power and the word “right” can mean either what is morally right or what one has the right to do.
In human terms, when the people who have the might do something, it can automatically come to be seen as morally right even if it really isn’t. This is true partly because no one can stop someone else who has a lot of power. And it is partly true because “the winners write the history”.
Example
To allow this invasion to happen will give a signal to every petty dictator that might is right.