The British Navy had established a blockade of the Delaware Bay to prevent the Americans from receiving war supplies through the port of Philadelphia.

This fleet includes over two hundred and forty cannons.

The Americans had then fortified the river with cheveaux-de-frise in the shipping channel.

To transport gunpowder and arms, Robert Morris of the Pennsylvania Committee of Safety had chartered the newly built brig, also called brigantine, Nancy and her captain, Hugh Montgomery, on March 1, 1776.

On March 14, 1776, John Barry had been commissioned Captain of the fourteen-gun Lexington in the Continental Navy.

In early June, the privateer Nancy had loaded supplies in the Caribbean islands of St. Thomas and St. Croix.

She then sailed for Philadelphia with "three hundred and eighty-six barrels of gunpowder, fifty fire-locks, one hundred and one hogsheads of rum, and sixty-two hogsheads of sugar, &c, on board".

In mid-June, Barry had been alerted by Morris that Nancy was headed his way, and would need protection since she had only an eleven-man crew and six cannons.

Barry was soon joined by the eighteen-gun Reprisal, captained by Lambert Wickes, and the eight-gun Wasp, captained by William Hallock, and headed for Cape May.

The British blockade forces are led by the twenty-eight-gun HMS Liverpool, captained by Henry Bellew, and include the thirty-two-gun HMS Orpheus, captained by Charles Hudson, and the sixteen-gun HMS Kingfisher, captained by Alexander Graeme.

Also at this time, the vanguard of the British fleet of over one hundred ships is set to enter New York Harbor on the morning of June 29.