Badeau, still on the staff of General Grant, began the first volume of a military history of the general, who vetted the manuscript as it was being written. Soon after Grant assumed the Presidency, General Badeau was sent to London and served as Secretary of Legation in the United States embassy in London, England, from May to December 1869, where he could continue working on Grant's military history. Early in the next year he was made bearer of government dispatches to Madrid, then in May he was returned to London as
Consul in 1870 and served in that capacity until September, 1881. While Badeau lived in England, he received Grant as a visitor on several occasions during the trip. In 1875 Badeau was nominated as
Minister to Belgium, and in 1881 he received appointment as
Minister to Denmark, but he declined both. From 1882 to 1884 he was U.S. Consul in
Havana, Cuba. Badeau resigned this appointment after alleging that officials in the
State Department were corrupt in their dealings with Cuba and Spain, and stating that the department took no action after he made his charges. Badeau then aided Grant in the preparation of
Grant's memoirs, but Grant dismissed him before the book was finished after they argued over the details of the legal agreement specifying how much Badeau would be paid and how he would be credited for his editing, research and fact checking. A bitter quarrel lay behind the creation of this agreement – one that would continue even after Grant's death. Grant was surprised when Badeau expressed his complaints and made demands of Grant. Among other concerns, Badeau had two main points of contention with Grant. The first, having committed much of his time and effort in assisting Grant, Badeau maintained that he had been detained from many of his other involvements for several months. The second, realizing that Grant's memoirs was going to be a monumental success, he feared that his multi-volume work on Grant would be obscured in the wake of their publication and release. Grant had earlier thought that it would be unfair to publish anything that would detract from Badeau's work. : Grant signed on 7 February 1885. A month later Badeau added his signature, and recorded the receipt of Grant's first payment: "Received of Genl. U. S. Grant $250, my share of $1,000 received by him this day on account of his book. 3 East 66th St. New York. March 2, 1885." As Grant's
Memoirs approached completion, having benefited from Badeau's extensive rewriting and additions to its earlier sections, he became convinced that sales would likely go far higher than the $30,000 envisioned in this agreement. With Grant failing badly, Badeau proposed a new arrangement in April 1885: he would complete the work at the price of $1,000 a month, plus 10% of the profits. Grant thought the offer too advantageous to Badeau and was additionally annoyed by press leaks that painted Badeau as the true author of the forthcoming work. Grant broke off relations with his long-time aide and refused to pay him the $10,000 called for in their agreement. When the sales of the
Memoirs skyrocketed past $30,000—they eventually brought $450,000—Badeau sued to get his money. Eventually Mrs. Grant paid him the originally agreed upon $10,000 plus interest of $1,200 (see Brooks D. Simpson article on Badeau in
American National Biography). (He subsequently settled with Grant's son
Frederick for $10,000, ==Author and editorialist==