The specific form/construction of the brass (or copper) rivets is a 20th-Century style of rivet. The object probably is a chunk of horse-harness, perhaps as old as the first 1/3rd of the 20th-Century or perhaps somewhat later. That's pretty old, but not old enough to be a "war relic."
By the way... welcome to Treasurenet, and to the What-Is-It forum, the best place on the internet for getting correct identifications of "mystery-objects."