As cities throughout the South move to take down monuments of Confederate leaders, the mayor of Nashville unveiled a plan this week for the city to honor an overlooked part of the Civil War era: the contributions and sacrifices of slaves.

Under the proposal, announced Tuesday by Mayor David Briley near a Union Army stronghold built by thousands of former slaves, green space would be carved out in the heart of Nashville and a historic site rich in African-American history would be preserved. He said it was time for Nashville to recognize its slavery past.

“Our country, our city has never really done what is necessary to acknowledge the sacrifice of the slaves in our country, to atone for what is and will be a great scar on our nation’s history, or to take steps toward reconciliation,” Mr. Briley said at a news conference near the stronghold, Fort Negley.