This is the first in the series of the U.S. Mint's ten-piece series of replicas of America's first medals, issued to commemorate the decisive military actions of the Revolutionary War. The original medal was struck in gold by the Paris mint and awarded to General George Washington for the Liberation of Boston in 1776. It is displayed in the Boston Public Library.
This pewter medal was issued in 1976, as part of the Bicentennial celebrations. It is the size of an U.S. Silver Dollar and is sealed inside a collectors coin holder. The obverse shows a bust of Washington, the reverse shows Washington on horseback with his army. In the background, the British ships are taking flight. The legend is "Hostibus Primo Fugatis", or "The First Time the Enemies took Flight".
The medal appears to be in excellent condition. I have not removed it from the holder.