On this day in 1775, the Siege of Boston began, right after the Battles of Lexington and Concord, which occurred the night before. The American Revolution would continue until the Americans won in September 1783.
In 1836, Congress passed a law which created the Wisconsin Territory. At the time, it still included what would later become Iowa Territory (that would break off in 1838). It would become the 30th state to enter the union 12 years later, in 1848.
On this day in 1861, Robert E. Lee resigned his commission in the United States Army, so he could command the troops in Virginia. He would be one of the top generals in the Confederate Army.
April 20th is a significant date to terrorists for several reasons (along with April 19th; please see the supporting link for more information about their ties). First, it's Adolph Hitler's birthday. Second, in 1985 there was a raid on the Covenant, the Sword, and the Arm of the Lord compound (one of the leaders, who had ties with Timothy McVeigh, was executed on April 19th, the day of the Oklahoma City bombing). In 1999, Eric Harris and Dylan Klebold chose this date to kill 13 people and injure 24 more in the Columbine Massacre.
On this date in 2010, the Deepwater Horizon oil well exploded in the Gulf of Mexico. Eleven workers were killed at the time, but the effects would carry on for months, as workers tried to contain the spill. In the meantime, the United States stopped drilling in the Gulf, which has had an effect on the United States economy.
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