List of Puerto Ricans missing in action in the Korean War The United States Department of Defense has estimated that approximately 61 , 000 Puerto Ricans served in the military during the Korean War , most of them volunteers . A total of 121 Puerto Rican soldiers were among the 8 , 200 people listed as missing in action ( MIA ) . This total does not include people of Puerto Rican descent who were born in the mainland of the United States . Spain officially ceded Puerto Rico to the United States under the terms of the 1898 Treaty of Paris which concluded the Spanish – American War . It is a United States territory and upon the outbreak of World War I , the Congress enacted the Jones – Shafroth Act , which gave Puerto Ricans American citizenship with certain limitations ( for example , Puerto Ricans are not allowed to vote in presidential elections ) . As a result , Puerto Ricans have participated in every major conflict involving the United States from World War I onward . Thousands of Puerto Ricans participated in these conflicts . Many lived and returned to their homeland , others were less fortunate and either died as a result of a hostile enemy action or have been listed as missing in action . The term " MIA " dates from 1946 and refers to a member of the armed services who is reported missing following a combat mission and whose status as to injury , capture , or death is unknown . The missing combatant must not have been otherwise accounted for as either killed in action or a prisoner of war . The Korean War was one of two major conflicts which accounted for the most Puerto Ricans missing in action , the other being the Vietnam War . Korean War . According to the online archive " All POW - MIA Korean War Casualties , " the total number of Puerto Rican casualties in the Korean War was 732 ; however , this total may vary slightly since some non - Puerto Ricans , such as Captain James W . Conner , were mistakenly included . Out of the more than 700 casualties suffered in the war , a total of 121 Puerto Rican men were listed as Missing in Action . It was during the Korean War that Puerto Ricans suffered the most casualties as members of an all - Hispanic volunteer unit : the 65th Infantry Regiment . One of the problems the unit faced was the language difference ; the common foot soldier spoke only Spanish , while the commanding officer s were mostly English - speaking . In September 1952 , the 65th Infantry was holding onto a hill known as " Outpost Kelly " until the People ' s Volunteer Army which had joined the North Koreans , overran the position . This became known as the Battle for Outpost Kelly . Twice , the 65th Regiment was overwhelmed by Chinese artillery and driven off . The Battle of Outpost Kelly accounted for 73 of the men missing in action from the total of 121 . Out of the 73 MIAs suffered by the regiment in the month of September , 50 of them occurred on the same day : September 18 . During the Korean War , two Puerto Ricans who were members of the United States Marine Corps were awarded the Navy Cross , the second highest medal after the Medal of Honor that can be awarded by the Department of the Navy . One of the recipients was Ramón Núñez - Juárez , who was listed as MIA and was posthumously awarded the medal . Núñez - Juárez ' s remains have never been recovered and a symbolic burial with full military honors was held on October 25 , 1970 . There is a headstone with his name inscribed above an empty grave in the Puerto Rico National Cemetery , located in Bayamon , Puerto Rico . His name is inscribed in El Monumento de la Recordación , a monument dedicated to the Puerto Ricans who have fallen in combat , located in San Juan , Puerto Rico . Puerto Ricans Missing in Action . The following is a list with the names , ranks and the date in which 121 Puerto Ricans were listed as " missing in action " in the Korean War . All of these men served within the ranks of the United States Army with the sole exception of Ramón Núñez - Juárez , who served in the Marines . Their names are inscribed in El Monumento de la Recordación ( The Wall of Remembrance ) located in San Juan , Puerto Rico .