Nearly 100 years after the Civil War began, its last surviving veteran, Albert Woolson, passed away in Duluth, at age 106.

Federal agencies deposited millions of Civil War records in National Archives and Records Administration (NARA) over the years. The originals for most of the records I am discussing are among those.

In Ken Burns’s newest documentary, the war for independence was also a civil war. Amid a bitter fight over history, its ...