Friction arose between Dana and the Tribune’s publisher and senior editor, Horace Greeley, due to the latter’s resentment of Dana’s unilateral decisions made during Greeley’s long absences.  The secession crisis during the winter of 1860-1861 heightened tensions further between the two men, as Greeley held out hope for compromise while Dana declared secession to be unconstitutional and a provocation for war.  On June 26, 1861, as the Confederate Congress prepared to convene in Richmond, Virginia, the next month, Dana began running a prominent editorial-page slogan urging Union troops:  “The Nation’s War-Cry!  Forward to Richmond!”  Greeley was at home recuperating from a knee injury, but he allowed the headline to continue running through July 4.  When the Union’s attempt to advance toward Richmond met with embarrassing failure later that month at the First Battle of Bull Run, many commentators blamed the Tribune, while Greeley blamed Dana.  In late March 1862, when Greeley informed the newspaper’s stockholders that they would have to choose between him and his managing editor, Dana resigned.

Secretary of War Edwin Stanton immediately hired Dana, ostensibly dispatching him to investigate payroll services in the Western Theatre, but secretly instructing him to determine if reports of General Ulysses S. Grant’s intoxication were true.  Dana was impressed by Grant’s modesty, honesty, and fairness, and insisted that the general’s binge drinking was infrequent and did not affect his military duties.  In 1863, Dana was named assistant secretary of war, and thereafter served as a mediator between Stanton, Grant, and President Abraham Lincoln.

At the end of the Civil War in April 1865, Dana accepted a position as editor of the Chicago Republican, where he introduced short paragraphs and humorous observations.  The reason for his departure from the newspaper in May 1866 was disputed, with friends blaming the journal’s bad financial state, and critics citing the editor’s desire for a lucrative patronage appointment with the New York Port Authority.  In 1867, with financial backing from wealthy Chicago friends, Dana purchased the New York Sun and the Associated Press wire service.  To balance the interests of the newspaper’s Republican stockholders with its readership consisting mainly of working-class Democrats, Dana announced that the Sun’s editorial stance would be independent of party.  Yet, his editorials consistently criticized the Grant administration (1869-1877), and increasingly moved toward the Democratic camp.

From 1870 until 1884, the Sun had the highest circulation among the city’s morning newspapers.  The journal covered labor issues extensively, and Dana’s editorials encouraged workers to establish cooperative ventures for housing and education.  In addition, the paper’s reporters covered a wide array of current events, including what became known as “human interest” stories, and set standards that other journalists tried to emulate.  Dana is still widely quoted today for his definition of news:  “When a dog bites a man, that is not news, but when a man bites a dog, that is news.” 

In 1884, Dana used his editorials to attack Governor Grover Cleveland of New York, the Democratic presidential nominee, and to support Benjamin Butler, the Greenback-Labor nominee.  Dana had failed to anticipate both his readership’s loyalty to the Democratic Party and competition from Joseph Pulitzer's New York World, which resulted in a dramatic 43% decline in the Sun’s circulation from 1884 to 1886.  Dana mortgaged his paper to buy new presses and doubled its length to eight pages (the same as the World’s).  He essentially conceded the loss of his working-class readership to the World, but added a new audience by backing the policies of pro-business Democrats.  The changed look and stance of the Sun halted its decline and sparked a limited increase in circulation, but the newspaper would never again be the formidable journalistic giant that it was in the 1870s.  Dana broke with the Democratic Party again in 1896 when it nominated William Jennings Bryan for president; this time, he endorsed the Republican candidate, William McKinley.  Dana died the next year in New York City.