Are you sure it wasn't "black-clad"? That would mean that they were dressed in black

I'm sure you meant "black-clad" which means they're wearing black clothing.

Yes, the original is here: http://www.economist.com/news/united-states/21711884-our-columnist-travels-americas-outgoing-defence-secretary-afghanistan-and-iraq and it is "black-clad" and it means "dressed in black clothing." Also, the first word is "pinning," with two n's. "Pining" is actually a completely different word with a different pronunciation. Medals fasten to clothing with a sharp pin in the back, and "pinning" a medal means "attaching the medal to somebody's clothing."