Answer the following question: Generate a question that has the following answer: Around 500 for the following movie plot: In 1944, American forces were closing in on the Japanese-occupied Philippines. The Japanese held around 500 American prisoners who had survived the Bataan Death March in a notorious POW camp at Cabanatuan and subjected them to brutal treatment and summary execution, as the Japanese view surrender as a disgrace. Many prisoners were also stricken with malaria. The film opens with the massacre of prisoners of war on Palawan by the Kempeitai, the Imperial Japanese military's secret police (though factually, it was committed by the Japanese Fourteenth Area Army). Meanwhile, at Lingayen Gulf, the 6th Ranger Battalion under Lt. Col Mucci is ordered by Lt. Gen. Walter Krueger to liberate all of the POWs at Cabanatuan prison camp before they are killed by the Japanese. The film chronicles the efforts of the Rangers, Alamo Scouts from the 6th Army and Filipino guerrillas as they undertake the Raid at Cabanatuan. Throughout the film, the viewpoint switches between the POWs at Cabanatuan, the Rangers, the Filipino resistance and the Japanese. In particular, the film covers the resistance work undertaken by nurse Margaret Utinsky, who smuggled medicine into the POW camps. The Kempeitai arrested her and sent her to Fort Santiago prison. She was eventually released, but spent six weeks recovering from gangrene as a result of injuries sustained from beatings.
Answer:
How many prisoners were being held by the Japanese?