After four years of strenuous activity of body and brain, it was not easy for Carleton to settle down at once to commonplace routine. Having exerted every nerve and feeling in so glorious a cause as our nation's salvation, every other cause and question seemed trivial in comparison. Succeeding such a series of excitements, it was difficult to lessen the momentum of mind and nerve in order to live, just like other plain people, quietly at home. One could not be drinking strong coffee all the time, nor could battle shocks come any longer every few weeks. The sudden collapse of the Confederacy, and the ending of the war, was like clapping the air-brakes instantaneously upon the Empire State Express while at full speed. While the air pressure might stop the wheels, there was danger of throwing the cars off their trucks. It took Carleton many months, and then only after strong exertion of the will, careful study of his diet and physical habits, to get down to the ordinary jog-trot of life and enjoy the commonplace. He occupied himself during the latter part of 1865 in completing his first book, which he entitled "My Days and Nights upon the Battle Field." This was meant to be one in a series of three volumes. He had written most of this, his first book, in camp and on the field. In form, it was an illustrated duodecimo of 312 pages, and was published by Ticknor and Fields, and later republished by Estes and Lauriat. It carries the story of the war, and of Carleton's personal participation in it in the Potomac and Mississippi River regions, down to the fall of Memphis in the summer of 1862. After this, followed another volume, entitled "Four Years of Fighting," full of personal observation in the army and navy, from the first battle of Bull Run to the fall of Richmond. This was a more ambitious work, of five hundred and fifty-eight, with an introduction of fifteen, pages. It contained a portrait and figure of the war correspondent, with pencil and note-book in hand. Published by Ticknor and Fields, it was reissued in 1882, by Estes and Lauriat, under the title of "Boys of '61." Carleton completed a careful revision of this work about a fortnight before his golden wedding, for another edition which appeared posthumously in October, 1896.