Here's a link to your button on the Waterbury Website. It is listed under the fashion/Eagle heading. There are a few things that differentiate your button from a military one, the main one being the corroded back. But, the other differences are in the details or lack of, on the front. The flukes of the anchor and the fact that the rope does not pass through the eye are the most notable ones. The curve of the wings and lack of feather detail is another. I would say that your button is probably from the last half of the 20th century.
As mentioned , there are many many different variations of these buttons and it can be challenging to tell the differences . Yours does look like a later type of dress or civilian type , Chris .