On Dec. 7, 1950, 1st Lt. Arnold R. Flook, an interrogator with the 181st Counter Intelligence Corps (CIC) Detachment attached to the 1st Marine Division (MarDiv), earned a Silver Star for actions taken during the Battle of Chosin Reservoir. Flook lost his life in the battle, becoming the only casualty for the 181st CIC Detachment during the Korean War.

Throughout the Korean War, the 181st CIC Detachment was attached to the 1st MarDiv, providing essential intelligence support to the division and its operations while simultaneously training them to conduct tactical CI. After first supporting the Marines for the Inchon landing (Operation Chromite) in September 1950, the 181st CIC participated in a second amphibious assault at Wonsan on the east coast of North Korea, beginning the Allied offensive above the 38th parallel. The North Korean People’s Army (NKPA) was in retreat, allowing Allied forces to push northward; however, unbeknownst to United Nations Forces was the growing presence of Chinese Communist Forces (CCF) who would stymie the Allied advance.

After meeting unrelenting resistance from CCF fighters throughout October and early November 1950, a temporary lull in fighting gave Allied troops a false sense of security, and they resumed their push further northward. As the Eighth U.S. Army pushed north from Chongchon in the northwest, they were soon met by the CCF in the Battle of Chongchon River. Meanwhile, in the northeast, Chinese fighters surprised the X Corps at Chosin Reservoir.

Between Nov. 27 and Dec. 13, the X Corps, under the command of Maj. Gen. Edward Almond, faced seventeen days of fierce fighting as they retreated to Hungnam on the east coast. As the 1st MarDiv began pushing further north in late November, Flook and the rest of the 181st CIC and headquarters staff moved to Hagaru-ri, an important X Corps supply center just south of the Chosin Reservoir. Intense fighting in the surrounding area led the command to order all U.S. troops to evacuate Hagaru-ri.