During World War 1, the US Navy borrowed binoculars from US citizens as part of their "Eyes for the Navy" program. Each borrowed binocular was engraved with a serial number and cataloged by the US Navy for return at the end of the war. This one became No 6467.
If the binoculars had not been lost, it was returned to the original owners with a single US dollar bill and a note from the then Assistant Secretary of the Navy... future US president, Franklin D. Roosevelt!
So that's how this German Goerz Trieder (produced in 1899) became a military bino in 1917, for use against the German Imperial Navy!