During the year 1777, the occupation of Philadelphia by the British army, under Gen. Howe, led to some activity on the part of the American navy. While Philadelphia had been in the possession of the Continentals, it had been a favorite naval rendezvous. Into the broad channel of the Delaware the American cruisers had been accustomed to retreat when the British naval force along the coast became threateningly active. At the broad wharves of Philadelphia, the men-of-war laid up to have necessary repairs made. In the rope-walks of the town, the cordage for the gallant Yankee ships was spun. In the busy shipyards along the Delaware, many of the frigates, provided for by the Act of 1775, were built. In the summer of 1777 all this was changed. Sir William Howe, at the head of an irresistible army, marched upon Philadelphia; and, defeating the American army at Brandywine, entered the city in triumph. The privateers and men-of-war scattered hastily, to avoid capture. Most of them fled down the Delaware; but a few, chiefly vessels still uncompleted, ascended the river. To cut off these vessels, the British immediately commenced the erection of batteries to command the channel of the river, and prevent any communication between the American vessels above and below Philadelphia. To check the erection of these batteries, the American vessels "Delaware" twenty-four, and "Andrea Doria" fourteen, together with one or two vessels flying the Pennsylvania flag, took up a position before the incomplete earthworks, and opened a heavy fire upon the soldiers employed in the trenches. So accurate was the aim of the American gunners, that work on the batteries was stopped. But, unluckily, the commander of the "Delaware," Capt. Alexander, had failed to reckon on the swift outflowing of the tide; and just as the sailors on that ship were becoming jubilant over the prospect of a victory, a mighty quiver throughout the ship told that she had been left on a shoal by the ebb tide. The enemy was not long in discovering the helpless condition of the "Delaware;" and field-pieces and siege-guns were brought down to the river-bank, until the luckless Americans saw themselves commanded by a heavy battery. In this unhappy predicament there was no course remaining but to strike their flag. Though the British had possession of Philadelphia, and virtually controlled the navigation of the river at that point, the Americans still held powerful positions at Red Bank and at Fort Mifflin, lower down the river. Against the former post the British sent an unsuccessful land expedition of Hessians, but against Fort Mifflin a naval expedition was despatched.