by James M. McPherson; Oxford University Press; 192 pages; $19.95.

The Princeton history professor James M. McPherson here follows his excellent 1988 history of the Civil War era, Battle Cry of Freedom , with a book of short, lucid essays about the war and Lincoln’s role in it. As the title suggests, the book has two intertwined subjects: the idea of the war as a second American Revolution and the role of Lincoln in guiding its purpose and outcome.

Was it really a kind of Revolution, or did it, as many have argued, change little or nothing? McPherson argues forcefully for the former. The war ended for good the South’s political domination of the nation, destroyed its slavery-based economic structure, and left blacks undeniably far freer and better off—at least temporarily. Moreover, it gave liberty itself a new meaning.

Liberty had always meant freedom from government intrusion; henceforth it would mean freedom of opportunity guarded by government power. Looking back a century and a quarter later, it is easy to forget how great the changes the war wrought were, especially since so much of what had been won was later lost in what McPherson calls a counterrevolution in themid-1870s.

A central theme connects all the essays about Lincoln and his leadership: that the very nature and purpose of the war changed from 1861 to 1865, and that Lincoln brilliantly perceived this and made the most of it. At first the war was limited, its only aim to put down an insurrection; it eventually evolved into total war, a struggle to the death in which neither side could survive unless the other was completely vanquished. The Union could not last if states were free to leave it; the South could not endure without disunion and slavery.

Lincoln knew what this meant as it happened. He understood that after 1863 he must turn to total-war generals like Sherman and Sheridan. Since the institutions of the South had to be smashed, emancipation would have to become a strategy, and once it was a strategy it must become a purpose of the war. He saw that emancipation would necessitate a new concept of liberty in America, and gave that concept eloquent, powerful voice. And with unbending single-mindedness he focused on winning the war while almost everyone around spoke of compromises that would have meant defeat.

The Emancipation Proclamation liberated not only slaves but also Lincoln himself—he was freed, in McPherson’s words, “from the agonizing contradiction between his ‘oft-expressed personal wish that all men everywhere could be free’ and his oath of office as president of a slaveholding republic. It fused the ‘organizing principle’ of liberty that guided Lincoln before 1861 with the ‘single central vision’ of Union that became his lodestar during the war.”

These masterly essays say a very great deal in a short space