On this day in 1999, two teenage gunmen kill 13 people in a shooting spree at Columbine High School in Littleton, Colorado, south of Denver.

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On this day in 1929 in Chicago, gunmen in the suspected employment of organized-crime boss Al Capone murder seven members of the George "Bugs" Moran North Siders gang in a garage on North Clark Street. The so-called St. Valentine's Day Massacre stirred a media storm centered on Capone and his illegal Prohibition-era activities and motivated federal authorities to redouble their efforts to find evidence incriminating enough to take him off the streets. Alphonse Capone was born in Brooklyn in 1899, the son of Italian immigrants from Naples. In 1921 his old friend Johnny Torrio lured him to Chicago, where Torrio had built up an impressive crime syndicate and was beginning to make a fortune on the illicit commerce of alcohol. In 1925, Torrio was shot four times by Bugs Moran and Hymie Weiss, who were associates of a gangster slain by Torrio's men. Capone was in Florida in February 1929 when he gave the go-ahead for the assassination of Bugs Moran. On February 13, a bootlegger called Moran and offered to sell him a truckload of high quality whiskey at a low price. Moran took the bait and the next morning pulled up to the delivery location where he was to meet several associates and purchase the whisky. He was running a little late, and just as he was pulling up to the garage he saw what looked like two policemen and two detectives get out of an unmarked car and head to the door. Thinking he had nearly avoided being caught in a police raid, Moran drove off. The four men, however, were Capone's assassins. Wearing their stolen police uniforms and heavily armed, Capone's henchmen surprised Moran's men, who agreed to line up against the wall. Thinking they had fallen prey to a routine police raid, they allowed themselves to be disarmed. A moment later, they were gunned down in a hail of shotgun and submachine-gun fire. Six were killed instantly, and the seventh survived for less than an hour.

Many historical events occurred on April 4th, and Russ Mitchell recaps them in this video clip from This Day In History. President William Henry Harrison became the first US President to die while in office when his cold turned into pneumonia. Congress passed and authorized what would become known as the American flag, with 13 strips, and then 20 stars with a blue background. Each state that would be added would add another star to the flag. Also, the first Mexican American, Henry Cisneros, became mayor of a major city, which was Texas. On Martin Luther King Jr.'s Memphis hotel balcony, James Earl Ray assassinated King.

After Napoleon Bonaparte failed to unite all of Europe under his rule, he was thrown off his throne by the neighboring nations during the War of Liberation on April 11th. This event along with others on April 11, is recapped in this video clip. The video clip, narrated by Russ Mitchell from This Day In History also includes the crowning of William III and Mary II as King and Queen of England, and the launch of Apollo 13. Also on April 11, Chinese officials agreed to release the crew of the plane that was involved in the US-China Spy Plane Incident, which killed a Chinese pilot.

The great San Francisco earthquake killed 3,000 people, Paul Revere's midnight ride took place, physicist, Albert Einstein died, and play ball began a Yankees and Red Sox game for the first time in This Day in History video. The date is April 18th. Paul Revere's ride resulted in the battles of Lexington and Concord and signaled the beginning of the Revolutionary War.

On this day in 1933, at the height of the Great Depression, Franklin Delano Roosevelt is inaugurated as the 32nd president of the United States. In his famous inaugural address, delivered outside the east wing of the U.S. Capitol, Roosevelt outlined his "New Deal"--an expansion of the federal government as an instrument of employment opportunity and welfare--and told Americans that "the only thing we have to fear is fear itself." Although it was a rainy day in Washington, and gusts of rain blew over Roosevelt as he spoke, he delivered a speech that radiated optimism and competence, and a broad majority of Americans united behind their new president and his radical economic proposals to lead the nation out of the Great Depression. Roosevelt had no trouble defeating President Herbert Hoover, who many blamed for the Depression, and the governor carried all but six states. During the next four months, the economy continued to decline, and when Roosevelt took office on March 4, 1933, most banks were closed, farms were suffering, 13 million workers were unemployed, and industrial production stood at just over half its 1929 level. Aided by a Democratic Congress, Roosevelt took prompt, decisive action, and most of his New Deal proposals, such as the Agricultural Adjustment Act, National Industrial Recovery Act, and creation of the Public Works Administration and Tennessee Valley Authority, were approved within his first 100 days in office. Although criticized by many in the business community, Roosevelt's progressive legislation improved America's economic climate, and in 1936 he easily won reelection.

Watch what happened on November 20 throughout history in this This Day in History video. On November 20, 1947, Princess Elizabeth of England married Lieutenant Philip Mountbatten, who was once prince of Greece and Denmark. On November 20, 1962, President John F. Kennedy removed a month long naval blockade of Cuba. This ended the Cuban Missile Crisis. On November 20, 2003, singer Michael Jackson was arrested on charges of child molestation. Jackson was later acquitted of the charges. Lastly, on November 20, 1945, Nazi officials were put on trial in Nuremberg, Germany. This was the first time where military leaders had to answer to the actions. The trials led to twenty-two indictments, mostly for crimes against humanity.