Essayons 1940's Jacket

Description

Essayons 1940's Jacket. Condition is "Used". Shipped with USPS Priority Mail.
The Corps of Engineers' oldest and most time honored insignia is the exclusive Essayons Button. It has not changed in basic design since the war of 1812. It is still the required button for the Army Engineers' uniform. Some web site has that statement.
This item is size small or even extra small.
Another website stated that factory on the label started 1940.
Obvious moth damage outside.
Pockets and lining are ok.
I do not understand the brass hooks on the waist.
I am also ignorant of the brass bars on the shoulders.  Maybe his rank in the service.
Found in California last year.