“STAND FIRM YE BOYS FROM MAINE: The 20th Maine and the Gettysburg Campaign,” by Thomas A. Desjardin, Thomas Publications, 1995, Hardcover, 239 pages, $28.

Charles Ayer, Brewer, age 22.

John Clifford, Bangor, farmer, age 18.

Amasa Fickett, Brewer, farmer, age 18.

Edward Frederick, age 21, Bangor.

Waldo Odlin, farmer, age 21, Bangor.

These are a few of the local men of the 20th Maine Regiment who fought on July 2, 1863, at the Battle of Little Round Top in Gettysburg, Pa.

The story of the 20th Maine began in the summer of 1862, when President Abraham Lincoln called for 300,000 more federal troops to squelch secession and bring the renegade Southern states back into the Union. Maine’s quota was to provide four regiments.

So many Maine men answered the call that the 16th through 19th regiments filled quickly. The extra men, a little more than 400, formed the 20th Maine. Formation of the 20th was so unexpected it was viewed as an orphan regiment whose men “claimed no single county or region of the state as its home.”

Few of the 20th Maine men had any experience in warfare. Ten were graduates of Bowdoin College; many were farmers, laborers and-or lumbermen. Initially, their colonel was Adelbert Ames of Rockland, but he was replaced by Col. Joshua Chamberlain of Brewer, a Bowdoin College professor with little knowledge of warfare. Several days before the battle, he suffered a severe case of heatstroke and was thought to be near death, so he arrived at the battlefield in an extremely weakened condition.

As the hour of confrontation drew near, the 15th Alabama, numbering about 400 men and commanded by Col. William Oates, moved into position on uneven, rocky ground. Oates had ordered 22 of his men to take canteens to a nearby farm for water; the men did not return. In the heat of the July day, the remaining troops began to suffer heat exhaustion, which may have been a critical factor in the outcome of the fight.

Other regiments from Pennsylvania, New York, Alabama and Texas were also involved in the battle.

Thus the stage was set for what was to become one of the most famous and most studied small unit actions in the history of warfare and which, almost from the moment the haze of gun smoke cleared from the battlefield, was destined to gather around it the trappings of legend.

In his book, Desjardin tells the story of that 90-minute battle from both sides in detail. He gives the reader the feelings and actions, gleaned from the diaries and letters, of the soldiers of the 20th Maine whose duty it was to stand their ground and of men of the 15th Alabama who had been ordered to take Little Round Top.

“Stand Firm Ye Boys From Maine” is amply supported by photographs and maps which help the reader to understand the maneuver which became known as Vincent’s Spur. Family historians will find the 20th Maine roster of particular interest — it includes the ages, occupations and marital status of the soldiers. The book contains an index and a detailed bibliography for those who want to read more on the subject.

“I peeled back the legend,” Desjardin said during a recent interview, “and started to find out much that was not true.”

The latter chapters of his book discuss the making of the legend of Little Round Top and its entry into popular culture with the 1974 publication of Michael Shaara’s Pulitzer Prize-winning novel “Killer Angels.” The recent film “Gettysburg,” based on Shaara’s book, adds fuel to the legend and has given Joshua Chamberlain the status of a minor cult figure.

“Stand Firm Ye Boys” would benefit from a broader sketch — in the introduction, perhaps — of the larger events leading to Gettysburg. It would help those of us with rusty Civil War knowledge to more easily place the events at Little Round Top in context.

Desjardin, who works for the National Park Service at Gettysburg, is at work on a second book, “The Round Tops at Gettysburg.”