Memorial Day began in the United States with the observation of Decoration Day, which was a day when citizens decorated the graves of Civil War soldiers. It was a day for parades and speeches, featuring local Civil War veterans. Over the decades, it has become much more, from honoring all military dead to honoring all the dead.
The American Civil War, or War of the Rebellion, or War Between the States, or War for Southern Independence--whatever your preferred term--is of great interest to many, evident by the number of books, magazines, movies, and websites one can find on the subject. I can't begin to do justice to number of websites in which the Civil War relates to genealogy. However, I can list some websites that have proven very helpful in the research of my Civil War ancestors and relatives. First off, the list of my known Civil War people can be found on my website's military page here and my husband's family's military page here. These individuals are either our direct ancestors or brothers of direct ancestors. This does not include in-laws or cousins who were in the war, of whom there were many. I think these lists give you an idea of the magnitude of the war: everyone who possibly could serve, did (or perhaps, if wealthy enough, paid someone to serve for them...but that's another story). And because whole neighborhoods of men served together in the same units, the consequences were quite devastating; whole communities lost the majority of their young men in battle or to disease. This war affected our country in a way that none of the subsequent wars could or did. (A bit of trivia: one of the effects was that from this point forward in American history, women outnumbered men; a statistic that continues today.) It's important to find out whatever you can about your ancestors or relatives that may have served in one of the great conflicts of history; because what happened to them ultimately affects who we are today.
The Civil War Soldiers and Sailor System website is a great place to verify that your ancestor served during this war. In searching for a soldier or sailor, you must use the exact spelling on their record to find them, so it may take some creativity on your part to find your man. Currently, only African-American sailors are listed in the sailors list. Once you find your soldier, his unit and company will be given, and you can click on the link to read about the history of the unit: where they served, traveled, and battled (sailors have information on enlistment dates and ships on which they served). In the upper left corner of the website, you will find a link marked "Tools." Clicking on it brings up a right-hand menu with information about the National Archives and ordering service and pension records. Military service records are indeed interesting, but it is the pension records that are most useful in genealogy, as they often list marriage dates, spouses' and children's names, and other relevant information.
If you would like to read more official correspondence regarding your ancestor's military unit, check out Cornell University Library's Making of America Project here. Scroll down to the bottom of the page and choose either Official Records of the Union and Confederate Navies in the War of the Rebellion or The War of the Rebellion: a Compilation of the Official Records of the Union and Confederate Armies. While it is unlikely that you will find your ancestor by name in either of these multi-volume online books (unless he was an officer), you certainly can trace his unit's movements and various engagements through the war. From this site I copied and pasted pages upon pages of my 4th-great-grandfather Joseph Josiah Robbins' unit, the 58th Regiment of the Pennsylvania Volunteers for my records.
Civil War Rosters is a private website that is a directory of Civil War Rosters and Muster Rolls that have been found on the Internet. Named one of Family Tree Magazine's 101 Best Websites for 2003, it is the only online location where I was able to find a mention of a possible burial place for my 3rd-great-grandfather, Sylvester Fredenburg.
Another site I use quite frequently is the Sons of Union Veterans of the Civil War National Graves Registration Database. Your ancestor need not be a Union veteran for his name to appear in this database; some Confederate veterans' graves are also recorded. You can freely search for your ancestors and relatives. If you would like to submit information, you must first register (for free). I am simply amazed at the number of Civil War veterans that are buried here in my home county of Spokane County, Washington...located far from any Civil War battlefields. The National Graves Registration Database lists veterans that died long after the war, not just those that died in or soon after from battle or disease. For this reason, you too may have a long list of Civil War veterans buried in your area.
An interesting site that also relies on submitters is Military History Online - Civil War Genealogy Database. Here you can freely search for and also submit your Civil War ancestor or relative, along with your contact information: name, e-mail address, website. You can edit or delete information as well.
On subscription websites, Ancestry has the Civil War Collection - a compilation of 26 databases. It also has the 1890 Veterans Schedules, a fragment of the 1890 U.S. Federal Census, and includes widows of Civil War veterans as well. Footnote contains Brady War Photographs, the Civil War Pensions Index, and Confederate Soldiers Service Records for Alabama, Texas, and Virgina in its Civil War-era collections.
For offline resources, check out the Family History Library's catalog Place Search for your ancestral locations (put the county name in the top box and the state name in the bottom box of the search page) and check out the cemeteries listed for that area. It may be that the Daughters of American Revolution or the Committee of Civil War Graves Registration transcribed Civil War graves in that county; the organization will be listed as the author of the cemetery records in the list of titles. If the title is on microfilm or microfiche, you can go to your local Family History Center (FHC) and for a small fee, have the microform shipped to the FHC from Salt Lake City for you to peruse. If the title is not filmed but is in print, go to your local FHC and ask for a "Request for Photocopies" form. For $4.00, volunteers in the Family History Library in Salt Lake City will look up your surname in the book and mail you the results. For an additional $2.00 a page, they will also send you photocopies. For many titles of other microfilms, microfiche, and books relating to the Civil War, go to the Keyword Search of the Family History Library's catalog and use the boolean method ("civil war" michigan; "civil war" mississippi; etc.).
For further reading and information, check out Cyndi's List of U.S. Civil War/War for Southern Independence sites here. Happy Hunting!