Short answers, pulled from the story.
A prisoner of war is a person held captive by a belligerent power during or immediately after an armed conflict. The earliest recorded usage of the phrase "prisoner of war" dates to 1610.
Under the Third Geneva Convention of 1949, POWs must be treated humanely, allowed to inform family and the International Committee of the Red Cross of their capture, given adequate food, clothing, housing, and medical care, paid for work performed, and released promptly after conflicts end. Article 17 states that POWs can only be required to give their name, date of birth, rank, and service number.
Of the approximately 132,134 Western Allied prisoners held by Japan, 35,756 died, a death rate of 27.1 percent, seven times that of Western POWs under the Germans and Italians. The 27,465 US Army POWs captured in the Pacific Theater had a 40.4 percent death rate.
The earliest known purpose-built prisoner-of-war camp was established at Norman Cross in Huntingdonshire, England in 1797, created to hold prisoners from the French Revolutionary Wars and Napoleonic Wars. Its average prison population was about 5,500 men.
About 56,000 of the 409,000 POWs died in prisons during the American Civil War, accounting for nearly 10 percent of the conflict's fatalities. At Andersonville, Georgia, 13,000 of the 45,000 Union prisoners confined there, or 28 percent, died.
The United States Military Code of Conduct was promulgated in 1955 via Executive Order 10631 under President Dwight D. Eisenhower. It was created primarily in response to the breakdown of leadership and organization among US forces held as POWs during the Korean War, and requires service members to resist providing information beyond name, rank, and serial number.