I doubt this movie is based on a true story. I saw on the movie it was based on a novel Lawsuit. And Gu Zidi is an imaginary character and you can't find any book about him. Yes his last name is Gu, which means "sorghium" in Chinese. And his name Gu Zidi means "a sorghium field" in Chinese. Did you see the captions at the end of the movie? It says that Gu died his parents when a baby and he was deserted in a sorghium field. So his adopted father gave him this name when picking him up. You can't be his distant relative unless your English family name is "Sorghium". haha I feel many western viewers didn't catch the point of this movie. The point is that a communist army officer felt cheated even betrayed when he learned that his long-desired assembly and retreat call had not existed at all and his 46 men may have died in vain because his superior had determined that their sacrifice would save the entire army. But personally, I doubt this theme. True his superior, Chen, didn't state clearly that they would not have any possibility of surviving the battle and there would not be any retreat call. But I still think their sacrifice is worthwhile. Anyway they covered the entire army's evacuation. I even guess this is a common practice in the war. By the way, the combat scenes of this movie impress me very much.
The movie states the main character was in fact a real person and that the mission of holding the mine was real too. The captions at the end stated he died somewhere in his 70's.