Now that his country had no ship to give him to do duty for America, he entered the service of his adopted State, Pennsylvania, and became "a bold privateer" by becoming commander of the Letter-of-Marque, the brig "Delaware," owned by Irwin & Co., of Philadelphia. His commission bears date of February 15, 1779. It is in the Lenox Library, New York.
The "Delaware" was a new brig of 200 tons, built to replace the schooner of the same name, which had been driven on the New Jersey shore and set on fire to escape the British early on the morning of November 21, 1777, when the State's Navy had passed up the Delaware River after the attack on Fort Mifflin.
The new "Delaware" carried ten guns and forty-five men when commissioned, but Captain Barry increased the force to twelve guns and sixty men.
The day he was commissioned he stood sponsor and his wife a witness to the baptism of Anna, daughter of Thomas, his brother, born on that morning. On July 21st following, Captain Barry's wife, Sarah Austin Barry, became a Catholic and was baptised, conditionally, Anna Barry, wife of Thomas, being the only sponsor. At this time Captain Barry was cruising in the West Indies. Judith, "the slave of Captain John Barry," an adult, was also baptised on August 19, 1779.
In the "Delaware" Captain Barry made two cruises to Port-au-Prince. Of his first voyage no record has been discovered, but of his second there is sufficient in the account given by his Mate, John Kessler. The "Delaware" sailed on its second cruise in the fall of 1779 in company with three other Letter-of-Marque brigs and one schooner. Of this fleet Captain Barry was made Commodore. He was always so appointed whenever two or more vessels were assigned to one cruise or expedition in which he engaged. When abreast of Cape Henlopen the British sloop-of-war the "Harlem," with eighty-five men and fourteen four-pounders, was taken without resistance, though the officers escaped in boats after heaving overboard all the guns.
The "Harlem" was sent to Philadelphia. The crew was delivered to the militia at Chincopague. Captain Barry reported to the owners that "the commanders in our little fleet are very complaisant and obliging to each other." That the "Harlem" had fourteen four-pounders and eighty-five men. The guns and other things were thrown overboard without firing a shot. The Captain, with ten men, went off in a whale-boat, "but," reported Captain Barry, "we have reason to think, is since overset." The prisoners were taken out, a prize crew put on board, the "Harlem" sent to Philadelphia and the men landed at Sinipaxan, Virginia, as they were too many to keep with safety on board the little fleet. "We have every reason in the world to think we shall catch more before long," reported Barry. The "Harlem" was "a fine vessel and had been a cruiser since the enemy took New York, but at present she is much out of tune," he added.