Transmigrate to the Great Qin: Mecha Sniper

In 210 BCE, Qin Shi Huang died. The eunuch Zhao Gao, Prince Hu Hai, and the high minister Li Si joined forces to alter the First Emperor's final decree, forging an imperial edict that ordered Prince Fusu, then serving with the army in Shang Commandery, to take his own life. The protagonist transmigrates at the moment Fusu commits suicide. Coming from a later age, the protagonist knows Zhao Gao forged the edict and heeds Meng Tian's advice. To counter Hu Hai's influence, he works with Meng Tian to steady the army in Shang Commandery, focus on farming, and quietly build up strength throughout Shang Commandery and along the Great Wall. To prepare for future expansion, he establishes the Protectorate of Anbei in Shang Commandery, governing the lands along and beyond the Great Wall. The Protectorate of Anbei announces a policy of reclaiming wasteland and establishing military farms. It attracts recluses, takes in refugees, and absorbs nomadic tribes, while also beginning construction of the city of Shang Commandery. The protagonist adopts policies unlike those of the First Emperor, correcting his hasty measures and overly aggressive national policies, and partially restoring the system of enfeoffment. He enfeoffs his brothers and sisters in various regions under the Protectorate of Anbei, where they establish their own states. The wheels of history cannot be turned back: Hu Hai still ascends the throne as the Second Emperor of Qin. Yet Hu Hai is deeply wary of Fusu and prepares to send an army against him. With Meng Tian's assistance, Fusu readies his forces for war. Fusu is merciful at heart and cannot bear to see brothers turn against one another, bringing widespread bloodshed to the newly established Qin Empire. He chooses to defend rather than attack, and his forces enter a standoff with the army sent by Hu Hai.