? Your first step should be to try to find what regiment your ancestor was in. The best sources for this are the 39-volume Roster of Union Soldiers, 1861-1865 and the 16-volume Roster of Confederate Soldiers, 1861-1865, both by Janet B. Hewett, available in major libraries. For the Union volumes, you'll need to know the state in which your ancestor might have joined the military; don't forget that regiments were often formed regionally, so men from Indiana might have joined an Ohio regiment, for example. Check neighboring states if you're not sure. These records are being put online at the Civil War Soldiers and Sailors System <www.itd.nps.gov/cwss>, an ongoing project administered by the National Parks System. Five states' rosters have been computerized to date.

? Once you know your ancestor's regiment, you can learn a lot more from regimental histories. Ask if your library has the microfiche of “Civil War Unit Histories” and “Regimental Histories of the American Civil War.” You may also find firsthand reports of your ancestor's unit in War of the Rebellion: A Compilation of the Official Records of the Union and Confederate Armies (known as the “OR” for “Official Records”) or its companion naval series.