One thing that you can’t say about George Washington is that he was a slacker. He was constantly communicating with people, whether it was the orders of the day, making plans to organize his army, or writing letters. And Washington was absolutely prolific at writing letters.
In this case, he’s writing to a Rhode Island merchant, thanking him for the advance notice of an incoming shipment, and reassuring him that the shipment will reach its destination safely, at least to the extent that he had any control over the matter.