Union Patriotic Cover

Gorham, Maine, 1864. unbound. Union patriotic cover with a large imprint of an angry Heraldic Eagle with stars & stripes shield, holding arrows in one talon and an olive branch in the other, draped with a banner marked "E. Pluribus Unum." Postmarked: "Gorham, Maine, July 13" with a cancelled 3c Washington (A-25) stamp, pink variety. No year, circa 1864, 3 x 5.5 inches. Small quarter-inch stain on the irregularly cut left margin, not affecting postmark. Good condition.