Major General William S. Rosecrans enjoyed a prominence and popularity in the middle of the Civil War equaled by few commanders on the Union side. After his successful fight at the Battle of Stones River on January 2, 1863, the Republican New York Times compared him to Napoleon and other great military minds of the past, declaring, “Gen. Rosecrans, if success be the standard, stands at the very head of the Union Generals.” Such examples of his contemporary fame and approbation, however, have largely been forgotten today. Rather, current opinions of “Old Rosy” have been shaped by his two notable failures: as a general at Chickamauga and as a subordinate of Major General Ulysses S. Grant. Grant’s extremely negative and often unfair criticism of Rosecrans in his famous Memoirs has strongly colored current perceptions of his rival, at a time when Grant’s own reputation is rising among most historians.
While many Civil War scholars and fans of the Western Theater will have heard of Rosecrans’s important victories at Iuka, Corinth, Murfreesboro, and Tullahoma, they have failed to realize that much of his popularity with Republicans also resulted from his well-known and outspoken opposition to slavery. It was this combination of battlefield success and strong support for the Emancipation Proclamation that led Horace Greeley to secretly sound him out for a potential presidential run in 1864. Even after Chickamauga, the Republican Chicago Tribune said, “Among all the Generals entertaining anti-slavery opinions, he has been the most outspoken; and among those willing to prove the sincerity of their word by the boldness of their acts, he has been the most successful.”
What did Rosecrans do to deserve such a reputation for being the most prominent anti-slavery general in the North? Certainly his antebellum background as a conservative Catholic Democrat made him an unlikely hero of Horace Greeley, Benjamin Wade, and other Radical Republicans. In short, Rosecrans’s allegiance to the Union was paramount. Like his friend the Catholic theologian Orestes A. Brownson, Rosecrans came to believe that the war for the Union could only be won by striking at slavery. After his Cincinnati friends Father Edward Purcell and Archbishop John Purcell came out strongly in favor of emancipation in Spring 1863, Rosecrans wrote a public letter supporting their position and attacking the peculiar institution. Widely reprinted in newspapers across the nation, including in a pro-Union pamphlet published by the Union League of Philadelphia, the letter helped secure his claim to be the North’s great anti-slavery general. Here is my transcription of that letter.
Murfreesboro, April 27, ’63.
My Dear Father Edward,
The Rebels grabbed the last letter that I wrote you, but they will draw very little consolation from its contents.
I am happy to see the splendid stand you take in The Telegraph, against slavery with its horrors, barbarities, and base immoralities. Slavery is dead. Nothing can resuscitate it. To learn this fact fully you should pay us a visit. There is not a negro in the South who does not know that he is free. Around here they have squatted on the plantations, and refuse to work for any one but themselves. They have sown little crops of their own, and the masters have ceased to exercise any control over them.
As an indication, I will cite a strong case. The lady of the house where I am staying, attempted to punish one of her negro women this morning. I had to step in to save the mistress from being badly used up, as the darkey was belaboring her with the stick intended for her own punishment. “Ex uno disce omnes.” It is needless for me to say that I applaud every sentiment expressed in the Telegraph. Your course is that of the prudent navigator, who, watching the black speck on the horizon, sees it expand into a portentous storm, and calls up his crew to take in sail and prepare for a contest with the elements. The storm will pass away, and you will be found sailing under full sail, while those who took not heed will be scattered by the gale.
I am heart and hand with you in this cause. Slavery is doomed, and those who would now uphold it will be held up in a very short time to public odium and execration. No statesman will vindicate it, no friend of human progress will stretch out a hand to break its fall, no lover of humanity and religion will grieve for its overthrow. I have lived long enough in the South, to see its workings, its disgusting features, debasing the higher principles of our nature, warring with religion, and patronizing vice and immorality. Almighty God has certainly ordained its destruction in this country, where it has been more offensive and immoral than in any other, and until it is utterly extinct, this war cannot, from the nature of things, cease. I am in favor of a cessation of hostilities at as early a day as possible; therefore, I am in favor of the President’s proclamation. This State was made for white people and free labor, and when slavery no longer blights its borders we may expect to see the church and the school take the place of slave-pen and market.
(William S. Rosecrans to Edward Purcell, April 27, 1863, (copy in hand of Annie E. Rosecrans), William S. Rosecrans Papers, Special Collections Library, University of California at Los Angeles; first published in Catholic Telegraph, May 6, 1863)
 New York Times, January 7, 1863; For a good example of recent positive scholarship on Grant that fully adopts his anti-Rosecrans arguments, see Ron Chernow’s Grant (New York: Penguin Press, 2017).
 William M. Lamers, The Edge of Glory: A Biography of General William S. Rosecrans, U.S.A. (New York: Harcourt, Brace & World, Inc., 1961), 259-60; Chicago Tribune, October 22, 1863.
 William B. Kurtz, Excommunicated from the Union: How the Civil War Created a Separate Catholic America (New York: Fordham University Press, 2016), 40-2, 94-5, 101-2; Catholic Telegraph (Cincinnati, Ohio), May 6, 1863; “Major Gen. Rosecrans on Slavery,” New York Daily Tribune, May 21, 1863; “Major General Rosecrans on Slavery,” New York Evangelist, June 11, 1863; “Gen. Rosecrans on Slavery,” Chicago Tribune, September 2, 1863; “Character and Results of the War. How to Prosecute It and How to End It. A Thrilling and Eloquent Speech,” (H.B. Ashmead, May 1863), Catalog Number II.6.015, Publications Committee Collection, The Heritage Center of the Union League of Philadelphia.