How to Find Out If an Ancestor Fought for the Union or Confederacy

1. Search the Civil War Soldiers and Sailors System (CWSS)

The National Park Service maintains the ultimate master index for Civil War participants, compiled from the millions of individual service cards stored at the National Archives.

• The Strategy: Search the free CWSS database using your ancestor's first and last name.

• The Proof: This database is highly specific. When you find a match, it will explicitly state whether the soldier served in the Union or Confederate army, their rank, and the exact regiment they fought with (e.g., "20th Regiment, Maine Infantry").

2. Analyze Their 1860 Census Location

Geography is often the strongest indicator of allegiance, though it is not a perfect rule—especially in "border states" like Missouri, Kentucky, or Maryland, where brothers famously fought against brothers.

• The Strategy: Use our Census & Population Collections to locate where your ancestor was living in the summer of 1860, just months before the war began.

• The Proof: If they were living deep in New York or Ohio, it is almost a statistical certainty they fought for the Union. If they lived in Georgia or Virginia, start your search in the Confederate archives. For border states, you must rely heavier on unit databases to confirm.

3. Check the 1890 Veterans Schedule

Most of the 1890 Federal Census was destroyed in a fire, but a special "Veterans Schedule" survived for many states.

• The Strategy: Search the 1890 Veterans Schedule for the county where your ancestor lived later in life.

• The Proof: This specific census was primarily designed to count Union veterans and their widows to help determine pension eligibility. While some Confederate veterans accidentally answered the census taker and were recorded, their names were usually crossed out. If your ancestor is listed clearly without a cross-out, they were Union.

4. Hunt for Pension Application Index Cards

Pensions were a massive post-war expense, and the paperwork generated is a goldmine for family historians.

• The Strategy: Search for your ancestor’s name in the "General Index to Pension Files."

• The Proof: For decades after the war, the federal government only granted pensions to Union veterans. If you find a federal pension card for your ancestor in our Military & War Records, they fought for the North. Confederate veterans had to rely on their individual Southern states for pensions much later in life, so those must be searched at the state archive level.

5. Review Death Certificates and Cemetery Records

Even if the government records are sparse, local communities and families proudly documented an ancestor's service in their final resting place.

• The Strategy: Locate your ancestor's death certificate or grave marker using our Vital Records Collections.

• The Proof: Look for specific abbreviations. Union graves often feature a "G.A.R." (Grand Army of the Republic) marker or mention it in the obituary. Confederate graves frequently feature a "U.C.V." (United Confederate Veterans) marker or an Iron Cross of Honor.