this translation comes from the Collection of Napoleon's Maxims, which contains maxims in two languages, in French and English. The Collection is by A. G. de Liancourt, and translated by J. A. Manning. Published: 1903, Arthur L. Humphreys, London. The collection can be found on internet.

I would suggest another interpretation of the saying. Taking into account the humble roots of Napoleon (he did not come from a wealthy aristocratic family), one can suggest that Napoleon is rejecting the kingly powers being justified by natural law reasons such as divine right. The divine right justifications for kingly power were used most often by a dynasty but sometimes also by a person from outside of a dynasty (such as in a case of a glorious victor popular with the masses). Lacking the “proper” birth, Napoleon could have utilized a justification coming from Nature by pointing to his victorious battles as a sign from God. He consciously chose not to do so and thus is a progenitor of truly civil power.

In regard to the standard translation question, I do not think there is one as this saying is not a very widespread and popular one in the English language. It would be perfectly fine to use the above mentioned official translation from 1903.