Vagrant Soldier Ares, Kingdom Recommendations
Both are war stories about a boy and his first experiences in battle. In Ares the protagonist loves to fight and seeks revenge and in Kingdom the protagonist wishes to fulfill his dream of becoming a general.
Both have alot of similar qualities. Really skilled young main characters, great character development, Giant war chapters, If you like Kingdom you will more then likely like Ares.
Both series focus on war and feature a bad-ass MC along with a cool cast of characters. Kingdom focuses more on stratagy and tactics while Ares more focuses on the duels, I reccomend reading both series to anyone who likes cool fights and military manga.