WAR ON THE WATERS: The Union and Confederate Navies, 1861-1865. By James M. McPherson. The University of North Carolina Press. 277 pages. $35.

“War on the Waters” is drama on the high seas indeed: a nation divided, lives to be lost and a war to be won.

In September 1864, U.S. Navy Captain Steedman wrote: “That little man” — he was speaking of Rear Admiral David Glasgow Farragut — “has done more to put down the rebellion than any general except Grant and Sherman.”

Author James McPherson, Pulitzer Prize winner and professor of U.S. History at Princeton, agrees with this assessment, stating that Farragut’s valiant and victorious naval battles “did indeed entitle him to equal status with Ulysses S. Grant and William T. Sherman in winning the war.”

The great land battles of the Civil War live in the nation’s consciousness, while the U.S. and Confederate navies’ contributions have drawn little attention. McPherson’s book is aimed at addressing this imbalance, and his account is informed and richly detailed, with maps that add much to the book.

To deny the Confederate’s access to their ports, and therefore their livelihood, the U.S. Navy had formed a blockade, “leaky as a sieve,” stretching from the Southeast coast through the waters as far west as Texas. However, their ships were few and often far between, cumbersome and slow.

Enter the Confederate navy, with its privateers, or blockade runners. Two of the most famous were the CSS Alabama and CSS Florida, built in England, just across the Mersey from Liverpool.

Lightweight, with shallow drafts, they could outrun the Union vessels. But as the U.S. Navy developed superior ships, such as the USS Monitor and USS Hartford, the tide turned.

Fierce sea battles ensued once the Union systematically began to capture the Southern ports, with Charleston being one of the most difficult, its defenses “like a porcupine’s hide,” according to U.S. Navy Captain DuPont, hero of the 1861 capture of Port Royal.

McPherson’s erudite prose and intimate knowledge of his subject makes “War on the Waters” an invaluable reference for Civil War scholars and laymen alike.

To write and understand Civil War battles, he is convinced that “one must go to the places where they occurred and walk the ground.”

McPherson concludes: “To say the Union navy won the Civil War would state the case much too strongly. But it is accurate to say that the war could not have been won without the contributions of the navy.”

Then this: “Without a blockade, the Confederacy might well have prevailed.”

Reviewer Frances Monaco is a writer in Charleston.