The Cambodian genocide

The massacres ended when the Vietnamese military invaded in 1978 and toppled the Khmer Rouge regime. By January 1979, 1.5 to 2 million people had died due to the Khmer Rouge's policies, including 200,000�"300,000 Chinese Cambodians, 90,000�"500,000 Cambodian Cham (who are mostly Muslim), and 20,000 Vietnamese Cambodians. 20,000 people passed through the Security Prison 21, one of the 196 prisons the Khmer Rouge operated, and only seven adults survived. The prisoners were taken to the Killing Fields, where they were executed (often with pickaxes, to save bullets) and buried in mass graves. Abduction and indoctrination of children was widespread, and many were persuaded or forced to commit atrocities. As of 2009, the Documentation Center of Cambodia has mapped 23,745 mass graves containing approximately 1.3 million suspected victims of execution. Direct execution is believed to account for up to 60% of the genocide's death toll, with other victims succumbing to starvation, exhaustion, or disease.

Border States: The states of Maryland, Delaware, Kentucky, and Missouri. Although these states did not officially join the Confederacy, many of their citizens supported the South.

Demonstration: A military movement which is used to draw the enemy's attention, distracting the enemy so that an attack can be made in another location.

Army: The largest organizational group of soldiers, made up of one or more corps. There were 16 Union armies (named after rivers, such as the Army of the Potomac) and 23 Confederate armies (named after states or regions, such as the Army of Northern Virginia). 1 company = 50 to 100 men, 10 companies = 1 regiment, about 4 regiments = 1 brigade, 2 to 5 brigades = 1 division, 2 or more divisions = 1 corps, 1 or more corps = 1 army.

Smoothbore: A gun is smoothbore if the inside of the barrel is completely smooth. Smoothbore guns were used before rifled guns were developed. Although smoothbores were not as accurate and had a shorter range than rifled arms, there were still plenty of them in use during the Civil War.

Torpedoes: Today called mines, Civil War torpedoes were mostly used by the Confederates. Sometimes they were buried in the ground in the enemy's path to explode when stepped on. Mostly they were used as water defenses. They floated below the surface of the water and exploded when the hull of a ship brushed against them.