SIFTING through the wreckage of the American Civil War has become a dangerous if irresistible occupation for historians.

The scale of interest in the US is such that bullets fly at those who commit the slightest of errors in regards to the detail or conduct of the war, or those who take a provocative approach to the conflict.

Richard Slotkin does both but rides into this unforgiving terrain with a lack of caution that suggests a literary style akin to riding a deranged charger straight towards the sound of fire. There have been complaints in the US that the historian has made errors, albeit slight ones to those far from the battlefield of Civil War criticism. However, his battleplan has reaped an outstanding victory. This is first-class history, written in an assured, occasionally flamboyant style.

It takes the story of one battle and uses it to illustrate the great decisions of the war and the marvellous, enduring follies of the human condition. George McClellan, the Union general, is the embodiment of the latter. McClellan was energetic in self-promotion, less so in his prosecution of a war. This produces the marvellous observation from Slotkin: "In his attempt to make his army an irresistible force, McClellan turned it into a nearly immoveable object."

Abraham Lincoln, a president under considerable pressure to resolve a conflict that was consuming the very fabric of a nation, became incensed at his general's strategy, which bordered on treachery.

This is the meat of Slotkin's historical feast. He uses the Battle of Antietam to illustrate the themes of a titanic conflict. The most significant lines of inquiry include the certain proposition that it was a test run for an invasion of the north by Confederate forces. Jefferson Davis and Robert E Lee wanted to bring the war to the Union and to influence other powers to broker a peace that would not be ruinous to the south. This strategy died on the field on Antietam.

Crucially, though, victory allowed Lincoln to make two huge decisions. First, he rid himself of McClellan, who was not only refusing to follow orders, he was also pursuing his own aims. McClellan was egocentric, arrogant and had delusions about being the saviour of the Union.

Second, the victory allowed Lincoln to issue the proclamation of emancipation. This ended equivocation over the fate of the slaves and signalled to the south that any peace would be on the Union's terms. It was one of the greatest moments in American history, and it is described with precision and flair by Slotkin.

The Long Road To Antietam, of course, continues in historical terms. The battle was fought in September 1862 but Slotkin's areas of interest still offer fertile ground for cultivation and the most intriguing aftertaste left by Slotkin's dramatic history concerns not the sloth of McClellan in pursuing victory or the general's intemperate ambition. It is this: Lincoln declared the emancipation of slaves in 1862 yet it took more than 100 years until a white, Democratic, Southern president in the shape of Lyndon B Johnson advanced the cause of the black man in the Great Society. His purpose was to make a fact out of Lincoln's proclamation. The long road from Antietam has not yet reached the destination of full freedom, although Slotkin is brilliant at recording the first steps.