According to historical records, including the Goryeo-sa, a 14th-century Korean chronicle, and the Yuan Dynasty's official history, the Mongols, under the command of General Choi Won, launched a surprise attack on the Goryeo army stationed at Jangsari. The Goryeo forces, despite being outnumbered, put up a fierce resistance. However, they ultimately suffered a crushing defeat, with General Kim Kyu-bu killed in action.

The unit assigned to this mission was the ROK Independent 1st Battalion, often referred to as the "772nd Unit" in historical accounts and popular media. The battalion was comprised largely of student volunteers—boys in their mid-to-late teens who had enlisted to defend their country. While they possessed high morale, they lacked the professional training and combat experience of the US Marines they were supporting.

Энэхүү аюултай даалгаварт ердөө хоёрхон долоо хоногийн бэлтгэл хийсэн, дунджаар 17 орчим насны 772 оюутан цэргүүд оролцдог. Тэд хангалттай зэвсэг, хоол хүнсгүй ч эх орныхоо төлөө эцсээ хүртэл тэмцэж буйг сэтгэл хөдөлгөмөөр харуулдаг. Меган Фокс дайны талбарт ажиллаж буй Америкийн сурвалжлагч бүсгүйн дүрийг бүтээсэн байдаг.

The moon hid behind smoke. The sea was the color of cold iron.