Strategy for the Warring States Period

There was no war in the Warring States Period, which is still a fantasy. What is needed here is not only extremely powerful combat power, but also super strong strategies and strategies to dominate everything here. A player is accidentally reborn in the game world. Facing the real people in the game, he cannot be indifferent, but if he wants to protect these people, he can only conquer the entire Warring States Period.