The following are five great traitors in American History:

• Benedict Arnold: Conspired to hand West Point over to the British (an action which would have greatly weakened the Continental's war effort during the American Revolution)
• Aaron Burr: Killed the President and later conspired to rule over a Western American Empire (which would have plunged the country into an East-West Civil War)
• John Anthony Walker: Led the Walker Spy Ring which sold ALL of the US war plans during the Vietnam War to the Soviets
• Aldrich Ames: Revealed to the Soviets the names of ALL the American spies currently operating in the Soviet Union. Many of them would be killed as a result.
• Robert Hanssen: Revealed to the Soviets the location where American leaders would hide in the event of nuclear war. Also sold the US missile launch plans in the event of a nuclear war.

For more information, read:
US News and World Report (Jan 27, 2003): Spy Stories
http://www.ushistory.org/valleyforge/served/arnold.html
http://www.crimelibrary.com/terrorists_spies/spies/ames/1.html
http://www.crimelibrary.com/terrorists_spies/spies/walker/1.html
http://www.usatoday.com/news/washington/2001-02-21-spydouble.htm

Military History Podcast is sponsored by Armchair General Magazine

1947 was a year filled with escalating tensions in the Cold War. This resulted in:

• Great Speeches: Truman Doctrine, Marshall Plan, Zhdanov's Two Camps
• Great Inventions: Presidential Succession Act, National Security Act (which created the CIA, DoD, Joint Chiefs, National Security Council), AK-47
• Great Beginnings: Indo-Pakistani War

It is also my dad's year of birth.

For more information, read:
The Cold War by Mike Sewell
The Timetables of History
Armchair General (May 2006): AK-47
http://www.jcs.mil/cjs_history.html
http://www.state.gov/r/pa/ho/time/cwr/17603.htm
http://www.americanrhetoric.com/speeches/harrystrumantrumandoctrine.html

Military History Podcast is sponsored by Armchair General Magazine

Though they are not the only great walls of history, the following four certainly rank high:

• Great Wall (Started around 200BC): This wall, which is 25 feet high and 25 feet thick, was built to keep Mongol Invaders out of China. It was equipped with many watchtowers and smoke signaling systems. However, this Wonder of the Medieval World is deteriorating due to weather and American corporate influence. Recently, the wall was cleared by a skateboarder (The first time a non-motorized vehicle cleared the Wall).
• Hadrians Wall (Started around 100AD): This wall, which was only 6 yards high, spanned across the entire width of Britain. It was used by the Romans to defend against Scottish tribes. The wall was supplanted by Roman garrisons and forts.
• Maginot Line (Built from 1930-1935): This line of forts was created along the Franco-German border, in order to stop an expected German offensive to the West. However, in WWII, the Germans simply went around the line via the Low Countries. Therefore, the term Maginot is associated with "something that is relied on but fails".
• Atlantic Wall (Built during WWII): This line of defenses was created by the Germans along the Atlantic Coasts of Norway and France. It was intended to deter an Allied amphibious invasion of Fortress Europe. However, the Allies still continued with their attack and were able to break through at Normandy. However, this massive collection of defensive tools greatly slowed the Allied advance.

For more information, read:
http://www.greatwallofchina.cn/
http://www.hadrians-wall.org/
http://www.maginot-line.com/
http://search.eb.com/dday/browse?browseId=237176
http://www.atlantikwall.net/
The Reader's Digest Illustrated History of WWII

Military History Podcast is sponsored by Armchair General Magazine