Reborn in 2001: Guardian of China

His comrades were killed and his mission failed. He breathed his last in desperation, only to open his eyes and find himself back in the rainy night of 2001. He remembered every enemy's face, every detail of his defeats, and—most importantly—the traitor hidden in the ranks was still alive. In this life, he sharpened his blade early, laid his plans ahead, and pulled his five doomed brothers back from the brink one by one. While the traitor still secretly passed intelligence at night, he was already waiting in the darkness. While foreign forces were still testing the limits, the boundary markers had already been set on borderlines they couldn't see. Their names are unknown, but their deeds are immortal. This time, all who should live will return alive. — Description from novelcodex.org