There are three Navy ships that had the name USS Wilkes, after Commodore Charles Wilkes.
This USS Wilkes, DD-67, was the second ship to bear the name. It was a Sampson-Class destroy and helped conduct operations throughout World War I.
The Coast Guard
In August, 1926, the Wilkes was transferred to the US Coast Guard and given the CG-25 Coast Guard number.
She served for eight years conducting Rum Patrols along the coast ranging from New England down to Florida during Prohibition.
In 1934, after Prohibition ended, she was transferred back to the US Navy and shortly after she was sold for scrap.
The cover was a letter from an E. Kastrup, who was stationed aboard the Wilkes during the time and location of the destroyer’s Coast Guard service. I’ve found no other info on Mr. Kastrup.