In signing this document the Revolutionary patriots knew that it meant war; and soon the struggle came,—­one of the inevitable and foreordained events of history,—­when Hamilton was still a college student.  He was eighteen when the battle of Lexington was fought; and he lost no time in joining the volunteers.  Dearborn and Stark from New Hampshire, Putnam and Arnold from Connecticut, and Greene from Rhode Island, all now resolved on independence, “liberty or death.”  Hamilton left his college walls to join a volunteer regiment of artillery, of which he soon became captain, from his knowledge of military science which he had been studying in anticipation of the contest.  In this capacity he was engaged in the battle of White Plains, the passage of the Raritan, and the battles at Princeton and Trenton.

When the army encamped at Morristown, in the gloomy winter of 1776-1777, his great abilities having been detected by the commander-in-chief, he was placed upon Washington’s staff, as aide-de-camp with the rank of lieutenant-colonel,—­a great honor for a boy of nineteen.  Yet he was not thus honored and promoted on account of remarkable military abilities, although, had he continued in active service, he would probably have distinguished himself as a general, for he had courage, energy, and decision; but he was selected by Washington on account of his marvellous intellectual powers.  So, half-aide and half-secretary, he became at once the confidential adviser of the General, and was employed by him not only in his multitudinous correspondence, but in difficult negotiations, and in those delicate duties which required discretion and tact.  He had those qualities which secured confidence,—­integrity, diligence, fidelity, and a premature wisdom.  He had brains and all those resources which would make him useful to his country.  Many there were who could fight as well as he, but there were few who had those high qualities on which the success of a campaign depended.  Thus he was sent to the camp of General Gates at Albany to demand the division of his forces and the reinforcement of the commander-in-chief, which Gates was very unwilling to accede to, for the capture of Burgoyne had turned his head.  He was then the most popular officer of the army, and even aspired to the chief command.  So he was inclined to evade the orders of his superior, under the plea of military necessity.  It required great tact in a young man to persuade an ambitious general to diminish his own authority; but Hamilton was successful in his mission, and won the admiration of Washington for his adroit management.  He was also very useful in the most critical period of the war in ferreting out conspiracies, cabala, and intrigues; for such there were, even against Washington, whose transcendent wisdom and patriotism were not then appreciated as they were afterwards.