FREEDOM By William Safire Doubleday. 1125 pp. $24.95

FOR AS LONG as I can remember I have been reading William Safire's Freedom, described by the publisher as "an epic novel of the Civil War." Covering the months between Abraham Lincoln's inauguration in March 1861 and the signing of the final Emancipation Proclamation on Jan. 1, 1863, Freedom is surely the longest work of fiction ever written about the Civil War. If you are heading for the beaches this summer, this is the only book you need to take with you; it will keep you fully absorbed for weeks.

Don't expect from it, though, what you would look for in most novels. It has no plot. Its only structure is the chronology of events. Every character appearing in its pages is an actual historical personage. Most are familiar figures like Lincoln, George B. McClellan, John C. Breckinridge, Salmon P. Chase and Ulysses S. Grant. But even the minor actors, like Rose Greenhow, the Confederate spy, and Anna Ella Carroll, the Maryland woman who claimed she originated the whole strategy of Union operations in the West, are real-life people. Freedom contains a good deal of made-up conversation, but most of it is a paraphrase of what these people are known to have said or written. The major exceptions are the love, or sex, scenes. Here Safire admits making the "salacious inference" that ex-President Millard Fillmore was sleeping with the virginal Dorothea Dix, that Anna Ella Carroll bedded down (among others) Vice President Breckinridge, and that Sen. Henry Wilson of Massachusetts enjoyed being whipped by Mrs. Greenhow. It could be argued that no author has the right thus to slander the dead, but Safire's efforts at fiction are so clumsy that certainly nobody will believe them. Fortunately, he drops these inappropriate efforts of invention after the first hundred or so pages.

The rest of Freedom is a detailed popular history of the first two years of Lincoln's administration. Safire has been studying the subject since at least 1979, and he has read widely in the printed literature and has even done some research in the unpublished manuscript materials. As evidence of his labors, he presents not merely an extensive bibliography but a 132-page "underbook," in which he "cites his sources, points out controversies, . . . justifies his own judgments, and makes clear where reporting ends and imagination begins." It is a pity that most general readers will probably neglect this section, which is written with the wit and acerbity that so often distinguish Safire's newspaper columns.

Safire's history appears to have three main purposes. First, he wants to present a new, or at least a different, picture of the wartime president. His Lincoln "is not Herndon's sly Lincoln, or Sandburg's saintly Lincoln, or the modern consensus Lincoln." He is, instead, a man obsessed with one "basic idea: if the experiment of this republic was to work, the majority had to rule -- all the time, with no exceptions." For this one purpose, a character in Freedom observes, Lincoln will "stretch the Constitution, he'll usurp the power of Congress and the courts, he'll change the system from a collection of states to a national power, he will free or not free the slaves . . ." The first two years of the Civil War shook Lincoln, drained him, aged and hardened him, but they left him even more convinced of the rightness of his goal and even more willing to move toward it "with little regard for personal affection or political loyalty . . . unencumbered by the barnacles of gratitude."

It is not clear why Safire thinks this view of Lincoln is novel. After all, the president himself explicitly declared that his "paramount object" was to save the Union so as to demonstrate that in this "last best hope of earth" democracy works. Nor does Safire explain how Lincoln's often arbitrary and sometimes extra-constitutional measures to save the Union are compatible with the president's insistence on majority rule. But perhaps these considerations do not matter in a work of fiction, and this characterization enables Safire to present Lincoln as the political equivalent of Captain Ahab -- clearsighted, utterly rational and a little demented.

SAFIRE'S second objective in this history somewhat contradicts the first: he wishes to show that the administration headed by this monomaniacal president moved ahead only by fits and starts, paralyzed most of the time by inexperience, ineptitude and internecine rivalries. Bringing to this account of the bureaucracy not merely his knowledge of the Civil War years but his experience as a newspaper reporter and a special assistant in the Nixon administration, Safire is at his best in portraying the muddle that goes by the name of government in Washington. His account of the factions and feuds in Lincoln's cabinet, with William H. Seward, Gideon Welles and Montgomery Blair pulling the president in one direction and Edwin M. Stanton and Salmon P. Chase tugging him in another, is as hilarious as it is accurate. The best pages in the book deal with the steps that led up to the issuing of the Emancipation Proclamation. That story of backing and filling, of reversals and changes in direction, of face-to-face argument and behind-the-scenes intrigue is a reminder that the national capital in the 1860s was not much different from what it is today; as the secretary of state recently remarked, nothing ever seems to get finally settled in Washington.

Exploring that continuity, that relationship between past issues and present-day problems, is the third objective of Safire's slightly fictionalized history. Set in the 1860s, Freedom also describes the 1980s. Should civilians or the military shape the foreign policy of the United States? (Safire, though more understanding of Gen. McClellan than some other recent writers, votes forthrightly for civilian control.) In times of emergency does the United States government have the right to suspend or circumvent normal judicial processes? (Safire writes that Lincoln's suspension of the privilege of the writ of habeas corpus "absurdly sacrifices the means to the end.") When the United States is locked in battle with an implacable, dangerous enemy, is it proper and desirable to suppress dissent? (Mr. Safire argues that "the thousands of arbitrary arrests did not help Lincoln win the war, and may well have been counterproductive.") Bluntly Mr. Safire concludes his story of the Lincoln administration with a judgment that clearly looks across more than a century toward Lt. Col. Oliver North, Adm. John Poindexter and their superiors: "The lesson . . .is that it is never a proper time to ignore the Constitution in the name of saving the Constitution. To be tolerant of Lincoln's excesses is to condone future abuses of power."

David Herbert Donald, Charles Warren Professor of American History and American Civilization at Harvard University, is the author of "Lincoln Reconsidered," "Charles Sumner and the Rights of Man" and many other books on the Civil War era.