Author Tom Ryan will present and sign copies of his book, “Spies, Scouts, and Secrets in the Gettysburg Campaign: How the Critical Role of Intelligence Impacted the Outcome of Lee's Invasion of the North, June-July 1863,” at 7 p.m. Sept. 28 at the Milton Historical Society, 210 Union St.

Ryan is the former president of the Central Delaware Civil War Round Table and a member of the Gettysburg Foundation and the Civil War Trust. He published more than 125 articles and book reviews on Civil War subjects and writes a weekly column called “Civil War Profiles” for Coastal Point, a Delaware newspaper.

The event is free for members and $5 others.

For more, visit historicmilton.org.