"Have you got your band on?"
William Sherman, a Union army General, with a mourning band tied around his arm
Public DomainWilliam Sherman, a Union army General, with a mourning band tied around his arm - Credit: Mathew Brady

Ulysses S. Grant, Lieutenant-General of the Union army, wearing a mourning band
Public DomainUlysses S. Grant, Lieutenant-General of the Union army, wearing a mourning band - Credit: Frederick Gutekunst
Grief
Public DomainGrief - Credit: Anna Ancher
Mourning bands made of black fabric (often crepe) are traditionally tied around the left upper arm as a sign of grief. Alternatively, they can be worn around the brim of a hat.