Tae Guk Gi: The Brotherhood of War (2004) on Netflix

In 1950, in South Korea, shoe-shiner Jin-tae Lee and his 18-year-old old student brother, Jin-seok Lee, form a poor but happy family with their mother, Jin-tae's fiancé Young-shin Kim, and her young sisters. Jin-tae and his mother are tough workers, who sacrifice themselves to send Jin-seok to the university. When North Korea invades the South, the family escapes to a relative's house in the country, but along their journey, Jin-seok is forced to join the army to fight in the front, and Jin-tae enlists too to protect his young brother. The commander promises Jin-tae that if he gets a medal he would release his brother, and Jin-tae becomes the braver soldier in the company. Along the bloody war between brothers, the relationship of Jin-seok with his older brother deteriorates leading to a dramatic and tragic end.