During a fall fraught with memorials to tragedies—light beams for Sept. 11; 700,000 white flags commemorating those who died from COVID-19 on the Mall—it would have been easy to overlook another D.C. milestone tied to national mourning: A hundred years since the burial of the Unknown Soldier. Built in 1921, following the first World War, the Tomb of the Unknown Soldier sits within Arlington National Cemetery, where it serves as a memorial to unidentified soldiers who died in combat. Urban Arias took notice. The inventive chamber opera troupe co-commissioned a song cycle to mark the centennial; the result will premiere on Oct. 5 at the Barns at Wolf Trap. (Additional commissioners include Opera Colorado, Minnesota Opera, and Opera Birmingham.) Composer Shawn E. Okpebholo and poet Marcus Amaker have written songs about war, honor, and memory to be sung by a mezzo-soprano (Taylor Raven) and two baritones (Michael Mayes and Schyler Vargas) who will take turns portraying soldiers, loved ones, and tomb guards. Wolf Traps’ reconstructed 18th century barns are sure to provide a haunting venue for the premiere, but for those who can’t make the trek to Vienna, a film version of Unknown will debut on Urban Arias’ website for Veterans Day where it will stream for free for a week. Unknown premieres on Oct 5, at 7:30 p.m. at The Barns at Wolf Trap, 1635 Trap Rd., Vienna, VA. $44. The free digital release will stream online from Nov. 11 to 18. urbanarias.org.