The Flowers of War (2011) on Netflix

In 1937, the cynical mortician John Miller arrives at a Catholic Church in Nanjing that is under protection of the Red Cross to bury the local priest during the Japanese attack to the Capital of China. He finds only student girls and one young boy in the convent and he decides to spend the night in the church and travel on the next day. Soon a group of prostitutes from the local brothel by the river breaks in the church seeking a sanctuary and they hide in the basement. On the next morning, a Japanese platoon breaks in the Church and when the soldiers see the girls, they try to rape them. John wears the priest costume and poses like a priest to the invaders. He tries unsuccessfully to stop the Japanese, but the Chinese Major Li (Dawei Tong), who is the only survivor of his troop, prepares traps using bombs and destroys the whole platoon. Now John needs to decide whether he leaves Nanjing in the last ship or stays in the church protecting the naive girls.