Mr. McCulloch resigned the position of Comptroller March 8, 1865, to accept appointment as Secretary of the Treasury, and served in the latter capacity until March, 1869. He was again appointed Secretary in October, 1884, by President Arthur, to fill the unexpired term of Secretary Gresham, who resigned to become a Circuit Court Judge of the United States.

In referring to his second appointment as Secretary of the Treasury, Mr. McCulloch, in his "Men and Measures of Half a Century," took occasion to express himself in the following complimentary terms of the personnel of the Department, and his appreciation of the valuable services rendered the Government and himself by his official subordinates during his connection with the Department:

I was glad to see among officers and clerks who called at my offices on the morning that I entered upon the discharge of my duties as Secretary, a number of familiar faces, although nearly fifteen years had passed since I had left the Department. I shall always hold in kind and grateful remembrance the men who served with me while I was Comptroller of the Currency and Secretary of the Treasury, in a very interesting and trying period of our financial history. An immense amount of work was done in that Department during the civil war and for some years after, and although it was done by men who had to learn as they worked, the record shows that it was fairly well done. Faithfully served as the Government was in the field, it was no less faithfully served by the officers and clerks in the public offices in Washington. There were among them men holding subordinate positions who were competent to fill the highest; men whose services could not be dispensed with without detriment to the Government; such men as would in Great Britain be retired with a pension when they were no longer able to perform their necessary work, instead of being turned out, as many have been, to give place to hungry applicants.

Thoroughly familiar with the details of the business of the Department himself, a most industrious worker, McCulloch readily recognized and appreciated ability, loyalty and industry in others, and unselfishly accorded credit where credit was due.