11 September 1813, Orange Court House. “As I am now about to leave for ever my native Country (of which you are the head) I can see no crime in submiting to you a few of my thoughts in the way of my profession.

“It is generally acknowledged War is the most necessary and useful of all the sciences. The various kinds of knowledge which ought to furnish the soldiers mind, are not without great difficulty to be attained. Of most other sciences the principles are fixed; and founded upon invariable combinations. Every man, even of a narrow understanding may remember rules, apply them properly, and sometimes draw just conclusions. But the science of War branches into so many particulars; it, takes in so many different parts; there are so many reflections necessary to be made, so many circumstances and cases to be brought together; that it is only by a continual application, grounded upon the love of his duty, and an inclination to his profession, that any officer can attain it. To march an army in every sort of Country, whether open, woody, or mountainous; to know how to form a camp in these countries, with which every officer of high Rank must be acquainted in order to do it with security; to make a proper disposition of a battle, whether with a view to the posture of the enemy, or the situation of the Country; to foresee events which depend in a measure upon chance; to be capable of making a good retreat on proper occasions is necessary to have seen much service; to direct the forages without fatigue or exposing the troops; to send out detachments with precuaution [sic], to conduct the convoys in safety; to know how to canton an army; to establish magazines in places, both safe from the enemy and convenient, to the army, so that it shall never be in want of assistance; are duties I hope your adjutant Generals, and Quartermaster Generals are fully competent to. Though I am sorry to say it appears the government have thought it sufficient for a military man to know how to obey; and for him to join the confidence of the soldiers to personal courage.

“Although bravery and courage are the most essential qualifications of a subordinate officer, yet he should not be deficient in those which are required in a general; for he knows not how soon circumstances may put him in a Gen’s command, particularly if he belongs to the Adj: Gen’s or Inspector Gen’s department, for there he frequently has to conduct columns, and in fact is the organ of the General.

“War is a trade and must be learnt like all others it supposes some qualities to be born with us, and demands others which are to be acquired. Ability whither in a Gen: or an inferior officer, is the effect of his genius, quickened by a natural liking to his profession, and the progress he has made is [sic] it. An Officer ignorent of his business and hot-headed however brave, can see nothing; or if he does it is a confused sight and that too late; for I have heard of Generals being taken prisoners when their armies have conquer’d; and hundreds of soldiers being taken by forty or fifty of the enemy. It is this quick eye united with that indispensable experience which enables an officer to judge of an advantageous post, of a manœuver to be made, and of a good disposition for the troops whether with respect to that of the enemy, or to the situation and nature of the Country.

“It is not less important to know how to take advantage of a rong movement of the enemy, than to know how to avoid them ourselves.

“But all the qualities I have mentioned would be useless, if Order and discipline were not severely observed; the army would be nothing more than a troop of Tartars acting more from the hope of plunder than the desire of glory, trusting each to his own head, or indulging his own humour would be cut in pieces party by party. What art and what experience is there not requisit to maintain this subordination. Why then do you frown upon the application of every old officer.

“No matter how much Sir, the honor of commanding troops may be sought after, it disgraces him who is not worthy of it; the titles of Capt. Maj: Col and Gen, so much desired, borders on the two extremes of glory and ignominy.

“That every officer in the Army may endeavour to copy some great Original who surmounted every difficulty, and merited the reward that always follow such irksome labours,” is Willis’s “fervent prayer.”

Adds in a postscript: “Sensible of the advantage I shall derive in Mexico from a certificate from you that I have been in the army during, the time you have been President of the U. S. and that I have conducted myself in a manner agreeable to you, I take the privilege of requesting that favor the last I shall ever ask. Should you grant it, a letter will reach me in Fredg.”