

This Civil War Union Patriotic cover I have had for about 10 years.
The datestamp reads May 7th, 1861, Rochester NY,
which was less than a month after the attack on
Fort Sumter on April 12th, 1861.
The stamp, Scott #26, is tied by a cork cancel,
a usage which fits with the 1861 date.
The printer of the patriotic envelope was R.E. Clark, Waverly Bookstore, Rochester NY,
which is consistent with the town cancel.