The Commoner-Born Imperial General Officer Rises Through the Ranks by Crushing His Incompetent Noble Superiors is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

All the bosses are annoying! The reincarnated strongest magician's trampling and subjugation begins! Hazen Heim, a newly appointed imperial general, is demoted to the front line because he is a commoner. There were a lot of incompetent people, such as "a trash superior who takes advantage of his position to steal the achievements of his subordinates", "an evil subordinate who keeps bullying people below him", and "a top who is too opportunistic to do anything''. However, Hazen has the experience and overwhelming ability as the strongest magician that he cultivated in his previous life. He slaughters his malevolent subordinates in accordance with military law, and completely refutes his superiors who complain. He achieved extraordinary results, such as making peace with a hostile tribe by teaming up with a genius girl, and defeated all the annoying bosses! An exhilarating upstart fantasy about an unscrupulous superior.