According to marilynmonroememories.co.uk:
While on honeymoon with Joe Dimaggio in 1954 they were invited to a cocktail party which was being given by the international set of Tokyo. A number of high ranking American army officers were there, and during the course of the evening one approached Marilyn and mentioned about a quick trip to the American troops fighting for the United Nations in Korea by Marilyn would be a great moral booster for the soldiers.
Marilyn was thrilled and agreed at once to the trip, Joe however thought it could be dangerous and was not happy about Marilyn going but Marilyn dismissed his fears by saying “it was the least anyone can do”.
So Marilyn was flown to Seoul, and then taken by helicopter towards the war area, snowflakes were falling during the flight, and the hillside was frosty. Marilyn Monroe asked if the helicopter could fly low so she would be able to wave to the soldiers. This she promptly did by lying face down on the floor of the helicopter, lowering her body outside the sliding door, while two soldiers sat on her feet. It is said that Marilyn was late at the DivisionHQ because she asked to fly over the troops a number of times.
Marilyn's travel outfit had been an olive shirt and pants, but she changed into a plum coloured dress covered in sequins before performing “Diamonds Are A Girl's Best Friend” on stage. Many soldiers were taking photographs of Marilyn on stage, and one soldier near the front was informed by Marilyn “honey, you forgot to take it off” (he had not removed the lens cap).
This live performance by Marilyn was one of the most recorded events at that time. That evening Marilyn attended dinner in the General's Mess.
By the time Marilyn reached 3rd Division she had moved from one unit to another meeting as many soldiers as she could, however it was noticed by the officers that the higher ranking officers were taking too much of her time, and after this was mentioned Marilyn Monroe was surrounded by enlisted men at meal times.
The amphitheatre of the 160th Regiment was another place that Marilyn performed, snow was falling lightly as Marilyn made her way to the stage. The troops were so moved by her being there that they stormed towards the stage and the performance had to be halted. A commander rushed on to the stage and told everyone “to get back as no one will see Marilyn Monroe until you do”!! It is worth noting that the other places that Marilyn performed for the troops at did see smaller riots, one soldier had to be taken in an ambulance as he had been trampled on.
A 2003 article from the L.A. Times talks of the effect Korea had on Marilyn:
In February 1954, she was at the height of her early popularity. She had yet to travel to New York to study acting with Lee Strasberg, which would lead to her classic roles in “Some Like It Hot” and “The Seven Year Itch.” But she would later say it was on the Korea trip, which produced near-riots among the servicemen, that she fully understood the effect she had on fans.
Korea “was the best thing that ever happened to me,” she would say. “I never felt like a star before in my heart.”
Photos on flickr here.