Early on the morning of the 4th of January, 1777, the three regiments commenced their march. The SEVENTEENTH regiment, commanded by Lieut.-Colonel Charles Mawhood, being in advance, encountered the van of the American army, General Washington having suddenly quitted Trenton with his whole force to surprise the three regiments. The morning being foggy, Lieut.-Colonel Mawhood could not discern the numbers of the force he had met; but supposing it to be only a detachment, he instantly attacked his opponents, and the SEVENTEENTH speedily drove back a force of very superior numbers with great gallantry. The regiment was soon environed in front and on both flanks by a numerous force; and Lieut.-Colonel Mawhood, discovering that he was engaged with the American army, resolved to make a desperate effort to extricate himself: having confidence in the valour and resolution of the regiment, he directed a charge with bayonets to the front, to break through the American army. Undismayed by the multitudes of opponents which environed them, the SEVENTEENTH rushed upon the ranks of the enemy, broke through all opposition, and continued their march to Maidenhead. Their conduct excited great admiration; and the Americans acknowledged the superior gallantry of the regiment. A serious loss was, however, sustained; thirteen officers and soldiers being killed, fifty-three wounded, and thirty-five missing: among the former was Captain the Honorable William Lesley, son of the Earl of Leven, an officer of great promise, whose death was much regretted. "The bravery and abilities of Colonel Mawhood, on this occasion, deservedly gained him the highest applause;"[9] and the resolute attack of the SEVENTEENTH so occupied the American army, that the fortieth and fifty-fifth regiments effected their retreat with much less loss than could have been expected. The American army had many men killed and wounded on this occasion; among the killed was an officer of reputation, Brigadier-General Mercer, from Virginia. When the army took the field, the regiment was employed in operations in the Jerseys to bring the American army to a general engagement; but General Washington kept close in his strong position in the mountains; and the British undertook an expedition to Pennsylvania: the SEVENTEENTH were employed in this enterprise, and were formed in brigade with the fifteenth, forty-second, and forty-fourth regiments, under Major-General (afterwards Earl) Grey. A landing was effected on the northern shore of Elk River on the 25th of August; and the army of the revolted provinces took up a position at _Brandywine_ to oppose the advance; an attack was made on the position on the 11th of September, when the Americans were driven from their ground with loss. On this occasion the SEVENTEENTH formed part of the column under Major-General Earl Cornwallis.