The French troops, under Rochambeau, marched from Newport and Boston toward the Hudson. Both in quarters and on the route their behavior was exemplary, and gained the respect and good will of the inhabitants. Toward the end of June (1781) Washington put his army in motion, and, learning that a royal detachment had passed into the Jerseys, he formed a plan to surprise the British posts on the north end of York Island, but it did not succeed, and General Lincoln, who commanded the Americans, being attacked by a strong British party, a sharp conflict ensued. Washington marched with his main body to support his detachment, but on his advance the British retired into their works at Kingsbridge. Rochambeau, then on his march to join Washington, detached the Duke de Lauzun with a body of men to support the attack, who advanced with his troops within supporting distance, but the British had retreated before they could be brought into action. Having failed in his design of surprising the British posts Washington withdrew to Valentine's Hill, and afterward to Dobb's Ferry. While encamped there, on the 6th of July (1781), the van of the long-expected French reinforcements under Rochambeau was seen winding down the neighboring heights. The arrival of these friendly strangers elevated the minds of the Americans, who received them with sincere congratulations. Washington labored, by personal attentions, to conciliate the good will of his allies, and used all the means in his power to prevent those mutual jealousies and irritations which frequently prevail between troops of different nations serving in the same army. An attack on New York was still meditated, and every exertion made to prepare for its execution, but with the determination, if it should prove impracticable, vigorously to prosecute some more attainable object. [1] On the evening of the 21st of July (1781), the greater part of the American, and part of the French troops, left their encampment, and marching rapidly during the night, appeared in order of battle before the British works at Kingsbridge, at 4 next morning. Washington and Rochambeau, with the general officers and engineers, viewed the British lines in their whole extent from right to left, and the same was again done next morning. But, on the afternoon of the 23d they returned to their former encampment without having made any attempt on the British works.