Adam Badeau (December 29, 1831 - March 19, 1895) was an author, Union Army officer, and diplomat.Adam Badeau was born in New York City on December 29, 1831. He was raised and educated in Tarrytown and North Tarrytown (now Sleepy Hollow), and became a clerk in New York City's Street Department. He also studied law, and attained admission to the bar in 1855. In addition, Badeau was a writer, and his work as an essayist and theater critic was published in Noah's Sunday Times.Badeau joined the Union Army for the American Civil War. As a member of the staff of Thomas W. Sherman, he took part in the Siege of Corinth, Mississippi, the defense of New Orleans and the attack on Port Hudson, Louisiana. He was wounded at Port Hudson, and after his recovery, in 1864 he joined the staff of Ulysses S. Grant as a brevet Lieutenant Colonel. Badeau took part in the Wilderness and Appomattox campaigns and received promotion to brevet Colonel. Badeau remained on Grant's staff until 1869, and left the Army with the full rank of Captain and the brevet rank of Brigadier General.Badeau served as Secretary of the United States embassy in London, England from 1869 to 1870, and U.S. Consul in London from 1870 to 1881. He was granted a leave of absence from 1877 to 1878, when he accompanied Grant on Grant's trip around the world. 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 left Grant before the book was finished over a dispute about how much Badeau would be paid and how he would be credited for his editing, research and fact checking. (He subsequently settled with Grant's heirs for $10,000, or about $250,000 in 2012 dollars.)