Joshua Lawrence Chamberlain, one of the major characters, remembers reciting to his father a speech from Hamlet: "What a piece of work is man...in action how like an angel!"

By threatening Washington, D.C., he hopes to draw the Union army into battle and inflict a crushing defeat, which will bring an end to the war.

Reynolds is killed and the Union troops are pushed back, but at nightfall they entrench on high ground while the Confederates celebrate what appears to them to be another in a long line of victories for General Lee.

Colonel Joshua Lawrence Chamberlain of Maine is told by his superiors that he occupies the end of the Union line, and that he must hold at any cost.

Knowing it is doomed, Longstreet argues against it, as his men will be forced to march across an open field under cannon fire to assault the well-entrenched Union center.

Beginning with the famous section about Longstreet's spy, Henry Thomas Harrison, gathering information about the movements and positions of the Federals, each day is told primarily from the perspectives of commanders of the two armies, including Robert E. Lee and James Longstreet for the Confederacy, and Joshua Lawrence Chamberlain and John Buford for the Union.

The author also uses the story of Gettysburg, the largest battle in the history of North America, to relate the causes of the Civil War and the motivations that led old friends to face each other on the battlefield.

Publication of The Killer Angels and release of the movie have had two significant influences on modern perceptions of the Civil War.

The filmmaker Ken Burns has mentioned the influence of the book in developing his interest in the Civil War and his subsequent production of the PBS series on the subject.

The Firefly science fiction television series was developed by Joss Whedon after reading The Killer Angels.

Singer-songwriter Steve Earle included a song on his 1999 bluegrass album, The Mountain, called "Dixieland", sung from the point of view of the character Buster Kilrain.

A second stage adaptation by Brian Newell, The Killer Angels, Soldiers of Gettysburg, opened May 5, 2017 at the Maverick Theater in Fullerton California.