The most deadly war in United States history was also known as the War Between the States. While it is most frequently said to have been over slavery, that is a vast oversimplification. The causes of the war included a myriad of other issues, not the least of which was the vast differences between the regions regarding economies, political values, social structure, and customs. The industrial revolution also played a part, as did states' rights. The war was fought from 1861 to 1865.
Regular Websites
This American Civil War website is provided by the Smithsonian Institution in Washington, DC. You can find it at that the institutions collections relating to the war including historical information on weapons, navies, slavery and abolition. You can also find out what was happening to the institution during the war. - American Civil War
http://civilwar.si.edu/
Contains sections about various battles, letters about the war, biographies of people who were instrumental in fighting, and strategy and tactics of the armies of both sides. - Civil War Home
http://www.civilwarhome.com/
History.com: American Civil War
The History Channel's treatment of the Civil War, with videos about various topics which address the war, the background both socially and culturally, and the issue of states' rights. - History.com: American Civil War
http://www.history.com/topics/american-civil-war
Illustrated London News: The Civil War in America
Provides scanned articles and illustrations which were published during the Civil War in the Illustrated London News. Additionally offers a bibliography and a search feature. - Illustrated London News: The Civil War in America
http://beck.library.emory.edu/iln/index.html
This website provides information about the papers of Jefferson Davis, an American historical figure best known as President of the Confederacy during the US Civil War. You can find a bibliography of published information on Davis here as well as a chronology of his life. - Jefferson Davis
http://jeffersondavis.rice.edu/
The Sons of Confederate Veterans is an American organization that seeks to keep the memory of the American confederacy alive. You can find out about the activities of the soldiers who fought for the south during the US civil war here. The website also has information on the organization's historical preservation activities. - Sons of Confederate Veterans
http://www.scv.org/
Contains thousands of pages of original Civil War content, photographs, illustrations and accounts from eye-witnesses. Includes complete papers of the Harper's Weekly newspaper with stunning illustrations and in-depth stories from prominent people and events. - The Civil War
http://www.sonofthesouth.net
Displays an atlas with maps of virtually every battle and campaign of the War of the Rebellion, browsable by state or by town. Also includes a timeline. - The War of Rebellion Atlas
http://contentdm.baylor.edu/cdm4/index_19wor.php?CISOROOT=/19wor
The website is dedicated to the only living and floating warship of the Civil War era, the USS Constellation. The website provides information regarding the USS Constellation history, the museum such as the tours and activities, overnight adventures at the ship as well as renting the ship for parties and receptions. The website also features a calendar of the activities held at the ship and also provides membership and volunteering info. - USS Constellation
http://www.historicships.org/
Presents a plethora of current photographs of Civil War battlefields as well as photographs originally taken during the war. Also has photographs and articles from re-enactments and from various parades and celebrations. - Virtual Civil War
http://www.mikelynaugh.com/VirtualCivilWar/