It was the bloodiest battle ever in the Western Hemisphere. For 3 days in July 1863 Americans slaughtered each other on a terrible scale around a small town in Pennsylvania, where the honored dead "gave the last full measure of devotion".

Find out why Robert E. Lee invaded the north, and why he failed so terribly; why the civil war dragged on for almost two more years after this union victory; and how this conflict inspired one of the greatest speeches ever in the English language.

Galileo is considered the father of modern science. His discoveries included the laws of pendulums which led to the development of the first accurate clocks. But tragically, he was tried by the Inquisition of Rome for heresy. The science deniers of the Church threatened to burn him at the stake unless he recanted his claims that he could prove that Copernicus was right: that the Earth is not the center of the universe, that we live in a heliocentric system where the earth and the other planets revolve around the sun.

A lot of elements contributed into winning World War II: Britain refusing to make peace with Nazi Germany after the fall of France along with the Chinese and Soviets willingness to suffer millions of deaths. But World War II was a war between the factories; whichever side could produce the most military equipment would win. The deciding factor in World War II was the fantastic industrial output of the U.S.

Polio was one of the scourges of the 20th century. And it mainly struck children. All of a sudden a person contracted polio and suffered terribly for several days; sometimes they recovered, sometimes they died, and sometimes they were left permanently disabled. The most famous polio victim of all time, Franklin Roosevelt, hid his disability from the public. But this story has a true hero: Jonas Salk, who developed a vaccine which led to the almost complete eradication of this dreaded disease. And Dr. Salk never patented the vaccine or earned any money from his discovery.

Wars are never solely military questions. They always involve politics and the will of the people. This episode outlines America's war in Vietnam and explains why the U.S. lost, including the limitations imposed by the American public and the realities of the Cold War.

The story of the Vietnam War usually starts with President John Kennedy being assassinated and new President Lyndon Johnson getting the U.S. into a long, unwinnable war from 1964 through 1973. This episode explores what happened before that war: the collapse of the French colony of Indochina, why Vietnam was split into 2 countries of North Vietnam and South Vietnam, why the communists tried to take over the South, and how did America become involved in the quagmire of Vietnam.

The Vikings are history's best example of an irresistible force. They were raiders from Scandinavia that pillaged and slaughtered across much of Europe. They founded Iceland, lived in Greenland, and were the first Europeans in North America. They changed Britain and most of mainland Europe. Find out what made them so formidable and how they reshaped the western world.

In the 1950s, U.S. Senator Joseph McCarthy led a hunt for Communists in the American government. His brand of persecution based on lies, rumors, and innuendos ruined many lives but did not send a single subversive to jail. He set the standard for politicians who wish to be bullies and demagogues.