A 1947 study found that during the Second World War, only about 15 to 25 percent of the American infantry ever fired their rifles in combat. (source)

In 1941, actress Hedy Lamarr and composer George Antheil were awarded a patent for a radio-controlled torpedo-guidance system. The United States navy later used the invention during World War II. (source)

The Wake Island rail was only discovered in 1903 and was extinct by 1946. It was wiped out when the island was occupied during World War II by Japanese soldiers, who found it a tasty delicacy. (source)

During World War I, a gun was invented by Jones Wister that could shoot around corners. It was never used, but a similar gun was used by Germans in World War II.

World War I was called "World War I" as early as 1919, 20 years before World War II began. (source)

A survey of 2,000 visitors to Blenheim Palace showed that half of them believed that Nelson commanded British troops at Waterloo, one in seven believed the Battle of Hastings to be fictitious and one in five believed that Harold Wilson was Britain's prime minister during the Second World War. (source)

During the Second World War, there was a secret project called Project Habbakuk, which planned to turn icebergs into aircraft carriers. No such aircraft carriers were ever produced. (source)

The last time the United States declared war was on June 5, 1942, during World War II, when it declared war on Hungary, Romania, and Bulgaria.

After the end of World War II, several Japanese soldiers still continued to hold out for years on remote islands in the Pacific, either not having heard about the Japanese surrender, or believing reports about it to be mere Allied propaganda. The last Japanese soldier to lay down arms was Private Teruo Nakamura, who surrendered in December 1974. (source)

The last shot fired in World War II was a torpedo, not a bullet. It was fired from the U.S. submarine Torsk at 9:17 p.m., August 14, 1945 (just before the official end of the war at 11:00 p.m.), during a battle against several Japanese ships. The shot sank a Japanese coastal defense frigate. (source)

After World War II, England was offered the Volkswagen business as part of reparations, but declined, believing that cars with engines at the back had no future. British occupation authorities, however, placed an order for 20,000 of the "Beetles" to help put the Volkswagen company back on its feet. By 1959, the company was producing nearly 4,000 cars every day.

It is untrue that carrots are good for your eyes. This belief started in World War II, when the British began using airborne radar, allowing them to find German bombers at night. In order to mislead the Germans, a rumour was spread indicating that John Cunningham, the Royal Air Force's most successful night fighter pilot, had developed phenomenal night sight by eating carrots in large quantities.

Japan likely would have surrendered in World War II even if the United States had not dropped atomic bombs on Hiroshima and Nagasaki. Even before atomic bombs were dropped on Japan, most of the high-ranking officials in the Japanese government had already decided that the war should be ended even if it meant surrendering, and in 1946 the United States War Department concluded that Japan would have surrendered sometime in 1945 even without the use of the atomic bomb. (source)

King Peter II of Yugoslavia is the only European monarch who is buried in the United States. He became king at the age of 11 in 1934, when his father, Alexander I, was assassinated. His uncle, Prince Paul, ruled Yugoslavia as regent for all of his reign except for the last ten days (after Paul signed an agreement with Hitler and Mussolini in March 1941). After World War II, Tito set up shop in Yugoslavia, leaving Peter without a kingdom. He died in Denver, Colorado on November 4, 1970 and is buried at the Serbian Church monastery in Libertyville, Illinois. (source)

In 1942–1943, Poon Lim survived on a raft floating on the Atlantic Ocean for 133 days. The ship he was on, the SS Ben Lomond, was torpedoed in the Atlantic Ocean near the Equator and around 300 miles off the coast of Brazil on November 23, 1942. He escaped on a raft and survived by catching fish and anything else that he stumbled upon and drank rainwater. He was rescued off Salinópolis, Brazil on April 5, 1943. He was awarded the British Empire Medal and the U.S. Congress voted him American citizenship. (source)

The Nazca lines in Peru are not the only pre-Columbian drawings only visible from the sky to be found in North America. In the southeastern California desert near Blythe is a 167-foot-long figure of a man. Other figures were visible before World War II, until Blythe was used as a military training area and tanks and other vehicles obliterated many of them. Dating methods have dated the figures to around the year 900, give or take 100 years. Interestingly enough, one of the remaining figures appears to look like a horse, but the horse was not present in North America around that time. (source)