I recall reading that Napoleon promoted enlisted men who showed conspicuous bravery to officers (I believe continuing a practice started by the French army during the revolution). The historian I read who discussed this practice said that the lack of education of these officers did prove a hindrance to the French at times, but there were also definite advantages to the practice; it produced officers who were conspicuously brave, and set a good example, and it gave the enlisted men incentive to try harder if promotion was possible. But perhaps the biggest benefit was that it guaranteed Napoleon could replace his losses; in most European countries at the time, only aristocrats could be military officers, and losses in the Napoleonic wars were high enough that some countries ran short of remotely suitable aristocrats to employ as military officers.

Enoch Powell rose from Private to Brigadier during the course of the Second World War., though this was very rare.

Do you have a reference on that?

Nope, and I am too lazy to go search, but it would be consistent with the early Soviet emphasis on egalitarianism and their need to construct an army almost from scratch.