The Battle of Antietam (icon; also known as the Battle of Sharpsburg, particularly in the South

Southern United States

The Southern United States—commonly referred to as the American South, Dixie, or simply the South—constitutes a large distinctive area in the southeastern and south-central United States...

), fought on September 17, 1862, near Sharpsburg, Maryland

Sharpsburg, Maryland

Sharpsburg is a town in Washington County, Maryland, United States, approximately south of Hagerstown. The population was 691 at the 2000 census....

, and Antietam Creek

Antietam Creek

Antietam Creek is a tributary of the Potomac River located in south central Pennsylvania and western Maryland in the United States, a region known as the Hagerstown Valley...

, as part of the Maryland Campaign

Maryland Campaign

The Maryland Campaign, or the Antietam Campaign is widely considered one of the major turning points of the American Civil War. Confederate Gen. Robert E. Lee's first invasion of the North was repulsed by Maj. Gen. George B...

, was the first major battle in the American Civil War

American Civil War

The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

 to take place on Northern

Northern United States

Northern United States, also sometimes the North, may refer to:* A particular grouping of states or regions of the United States of America. The United States Census Bureau divides some of the northernmost United States into the Midwest Region and the Northeast Region...

 soil. It was the bloodiest single-day battle in American history

History of the United States

The history of the United States traditionally starts with the Declaration of Independence in the year 1776, although its territory was inhabited by Native Americans since prehistoric times and then by European colonists who followed the voyages of Christopher Columbus starting in 1492. The...

, with about 23,000 casualties.

After pursuing Confederate

Confederate States Army

The Confederate States Army was the army of the Confederate States of America while the Confederacy existed during the American Civil War. On February 8, 1861, delegates from the seven Deep South states which had already declared their secession from the United States of America adopted the...

 General Robert E. Lee

Robert E. Lee

Robert Edward Lee was a career military officer who is best known for having commanded the Confederate Army of Northern Virginia in the American Civil War....

 into Maryland

Maryland

Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

, Union Army

Union Army

The Union Army was the land force that fought for the Union during the American Civil War. It was also known as the Federal Army, the U.S. Army, the Northern Army and the National Army...

 Maj. Gen.

Major general (United States)

In the United States Army, United States Marine Corps, and United States Air Force, major general is a two-star general-officer rank, with the pay grade of O-8. Major general ranks above brigadier general and below lieutenant general...

 George B. McClellan

George B. McClellan

George Brinton McClellan was a major general during the American Civil War. He organized the famous Army of the Potomac and served briefly as the general-in-chief of the Union Army. Early in the war, McClellan played an important role in raising a well-trained and organized army for the Union...

 launched attacks against Lee's army, in defensive positions behind Antietam Creek.