He was a constant student and a ready writer, and during this time published a number of military and scientific books, some of which were original and others translations. Intellectually, professionally and socially he stood very high, and the bestowal of a Major-General's commission upon him, dating from Aug. 19,1861, met with universal approval, though it gave him seniority in that coveted rank to many distinguished soldiers. At that time Halleck was in his 46th year and the very prime of his powers. He was tall, spare, and commanding in figure, with a clean-shaven, authoritative, intellectual face in which men read great things. He had large, searching eyes, which seemed to penetrate the one with whom he was talking. As far as education and observation could go, Halleck was as complete a soldier as could be produced. Whatever could be done by calculation and careful operation, he could do on a high plane. He only lacked military instinct and soldierly intuition. Of that moral force which frequently overleaps mere physical limitation he seems to have had little, nor could he understand it in others. There was in him none of the fiery zeal of Lyon, or the relentless pugnacity of Grant; apparently these qualities were so absent in him that he did not know how to deal with them in others. He never put himself at the head of his troops to lead them in battle. 255 He could build up, block by block, with patient calculation, without comprehension that somewhere might be a volcanic energy suddenly unloosed which would scatter his blocks like straws. If he had political convictions, they were so unobtrusive as to be rarely mentioned in connection with him. Probably his views were the same as generally prevailed among the Regular Army officers of that day which were represented by the attitude of the Douglas Democrats and "Old Line Whigs." He believed, above all things, in law and system, and wanted all the affairs of this world to go ahead in strict accordance with them. The soldier epithet of "Old Brains" was bestowed upon him, and he seemed to relish the appellation. In the long and specific letter of instructions accompanying his assignment to command, Gen. McClellan directed him to carefully scrutinize all commissions and appointments, and revoke those not proceeding from the President or Secretary of War; to stop all pay and allowances to them, and if the appointees gave any trouble, send them out of the Department, and if they returned, place them in confinement. He was to examine into the legality of all organizations of troops serving in the Department, and deal with those unauthorized in a similar summary way. All contracts were to be rigidly probed, and payment suspended on those of which there was the slightest doubt. All officers who had in any way violated their duty to the Government were to be arrested and brought to prompt trial. 256