Furthermore,

Mercenaries and auxiliaries are useless and dangerous; and if one holds his state based on these arms, he will stand neither firm nor safe; for they are disunited, ambitious and without discipline, unfaithful, valiant before friends, cowardly before enemies

-- Machiavelli in the Prince

Not to call out Putin’s Russia for being amateur hour, but the Prince is probably the first thing to read for an aspiring dictator.