[Footnote 1:  See note No.  I. at the end of the volume.]

[Sidenote:  May 1.]

Not long after this incursion into Jersey, an enterprise was undertaken against General Lacy, who, with a small number of Pennsylvania militia, seldom amounting to six hundred, and sometimes not exceeding fifty, watched the roads leading to Philadelphia on the north side of the Schuylkill, and was generally posted within twenty miles of that town.

[Sidenote:  General Lacy surprised.]

This expedition was entrusted to Colonel Abercrombie and Major Simcoe, who avoided all the posts Lacy had established for his security, and threw a body of troops into his rear before he discovered their approach.  After a short resistance, he escaped with the loss of a few men killed, and all his baggage.  His corps were entirely dispersed, and he was soon afterwards relieved by General Potter.

To maintain the command of the water as far as was practicable, congress had ordered impediments to be sunk in many of the rivers of common use, so as to obstruct the passage up them, and had constructed frigates, and other smaller vessels, to be employed above those impediments or elsewhere, as the occasion might require.  Several of them had been commenced above Philadelphia, but were not completed when the British obtained the command of the river.  General Washington then became apprehensive for their safety, and repeatedly expressed his desire that they should be sunk in such a manner as to be weighed with difficulty, should any attempt be made to raise them.  The persons, however, who were entrusted by congress with this business, supposed it would be equally secure to put plugs in their bottoms, which might be drawn out on the approach of danger.

Against these vessels, and some stores collected at Bordentown, an expedition was planned which ended in their total destruction.  General Dickenson was in the neighbourhood, but his force was too small to interrupt the execution of the design; and General Maxwell, who had been ordered to his assistance, was retarded in his march by a heavy rain, which did not obstruct the movement of the British, who passed up the river in vessels.

[Sidenote:  May 18.]

To cover the country more effectually on the north of the Schuylkill, to form an advance guard for the security of the main army, and to be in readiness to annoy the rear of the enemy, should he evacuate Philadelphia, an event believed to be in contemplation, General Washington detached the Marquis de Lafayette, with more than two thousand choice troops, to take post near the lines.  As this corps formed a very valuable part of the army, the Commander-in-chief recommended in his instructions to General Lafayette the utmost attention to its safety; and, particularly, to avoid any permanent station, as a long continuance in one position would facilitate the execution of measures which might be concerted against him.