RICHMOND, Virginia — One museum has among its vast Confederate-centric collection Thomas “Stonewall” Jackson’s sword and the flag that flew at Robert E. Lee’s headquarters. The other museum strives to tell the story of the American Civil War through the eyes of Northerners and Southerners, freed and enslaved blacks, soldiers and civilians.

Now the Museum of the Confederacy and the American Civil War Center are joining forces to build a $30 million museum in Richmond with the goal of creating the top Civil War museum in the nation 150 years after the deadliest conflict fought on U.S. soil from 1861-65 between the Northern states and the secessionist, pro-slavery Southern states.

The marriage of museums, announced to The Associated Press, will meld the collection of Confederate battle flags, uniforms, weapons and other historic relics with a narrative-based museum that uses bold, interactive exhibits and living history events to relate its 360-degree telling of the war.

What some might view as an unlikely partnership “makes so much sense” to Christy Coleman, president of the American Civil War Center, which opened in 2000 at a site where the new museum will rise....