There are a substantial number of reputable sites covering various topics related to the United States Civil War, such as causes, course, and its immediate aftermath. A limited selection is provided below to serve as a launching point for further research and discovery.
Civil War @ Smithsonian, Smithsonian National Museum of American History
An online exhibit "dedicated to examining the Civil War through the Smithsonian Institution's extensive and manifold collections". Civil War era topics covered include slavery and abolition, leaders, soldiering, life and culture, and more. A timeline covering period 1859 - 1865 is also provided.
No search interface is provided. Instead search by clicking on 'Collections' (on the left sidebar) and then browse through any of the twelve collections. The timeline is a separate tab and is also located on the left sidebar.
Each specific collection has its own search interface, but generally one can search the collections by keyword(s), title, subject index, author, or archival collections.
Civil War Soldiers and Sailors Database, National Park Service
Database containing information about the men who served in the Union and Confederate armies during the Civil War, narrative histories of Union and Confederate regiments, links to descriptions of significant battles and monument graphical images, and selected lists of prisoner-of-war and cemetery records.
Each category has its own specific search interface, but all are user-friendly. To search within a category follow these steps:
(1) Click on the category you are interested in (e.g., battles); (2) Click on 'Explore these records'; (3) Search options will vary depending on the category being searched, but all are designed to be searched by selecting from drop-down menus.
Hosted by the University of Pennsylvania Libraries and created with the support of the Library Company of Philadelphia this collection of primary material is useful in the study of the political, economic, social, religious, racial and gender issues from the Civil War era. The collection is comprised of pamphlets, books, broadsides, cartoons, clippings, paintings, maps, and other print memorabilia.
A robust search interface is available. You can search within this resource for information on Civil War history any of the following four ways:
Discovering the Civil War, National Archives and Records Administration
A resource page that provides direct links to related Civil War content available at the National Archives in a variety of formats. A selection of what you can find follows:
No search interface is provided. Rather one navigates the site by browsing through available entry titles.
Hosted by the University of Michigan, this is a digital library of primary sources of approximately 10,000 books and 50,000 journal articles with 19th century imprints covering the time period from the antebellum period through reconstruction, 1850-1877.
A sophisticated search interface is available. You can search within this resource for information on Civil War history either of two ways: