In his 1991 biography of Jefferson Davis, noted Civil War historian William C. Davis wrote that the future Confederate president’s years as U.S. secretary of War “generated nothing we remember or care about today.”

Davis the historian is one of my favorite writers, but in this case, he was dead wrong about Davis the secretary of War.

During his tenure at the head of the War Department during the administration of President Franklin Pierce, Davis was the driving force behind the expansion of the Capitol into the architectural landmark that we know today.

Even before he officially took over the project as the civilian administrator in charge of the Army Corps of Engineers, Davis had pushed the project as a Senator. The growing nation — and growing Congress — Davis argued, needed a bigger home for its legislature.

If it seems contradictory that the man who would one day lead a rebellion against the government whose seat was that same Capitol, that is only the beginning of the contradiction that is Jefferson Davis, whose enigmatic journey through the 1850s is the central human narrative in “Freedom’s Cap: The United States Capitol and the Coming of the Civil War.”

“From 1850 until the day he abandoned Washington to become president of the Confederacy eleven years later, Davis would be the new Capitol’s political champion, benefactor, and shepherd,” writes Guy Gugliotta, who once covered Congress for the Washington Post. “Without him the modern Capitol, recognized throughout the world as an enduring symbol of republican democracy, would never have existed.”

Gugliotta’s fondness for the building is evident on nearly every page, as he recounts the travails of those besides Davis who had a hand in the building of the House and Senate extensions and the new Dome.

In many ways it is a sordid tale of professional jealousy, partisan bickering, underhanded dealing, labor strife and cost overruns. Plus ça change, plus c’est la même chose.

But in a deeper sense, “Freedom’s Cap” is a beautiful story about the triumph of republican government and the men devoted to it, none more than the Army engineer in charge, Capt. Montgomery C. Meigs.

The debt owed to Meigs by the nation’s capital is almost too great to measure.

He led the building of the Washington Aqueduct, which first brought a regular supply of fresh water to the city. Later, it was Meigs who conceived of turning Robert E. Lee’s former home into a national cemetery for fallen soldiers.

And Meigs’ devotion to the expansion of the Capitol was second only to that of Davis.

He hired the workers, stood up to the carping Congressmen (with help from Davis, who suffered fools not at all) and brought in the artists and artisans — including Constantino Brumidi — who turned what might have been just another federal building project into a master work.

“For Meigs, the Capitol was less a meeting hall than a cathedral — an enduring and unforgettable monument to the greatness, not only of God and the Republic, but also of Montgomery C. Meigs,” Gugliotta writes.

He had offers to leave the Army and take other jobs for more money. He would have none of it.

“I was in charge of the … architecture and the greatest work of a civil engineer in the country,” Meigs wrote in his diary. “I preferred finishing that for nothing to going to take a similar work for a good salary.”

Everyone who works in and around the Capitol should read this wonderful book.

It is no easy thing to tell such a story in the context of its turbulent times without losing the story in the times. Gugliotta strikes a perfect balance, placing the Capitol project in the political context of the 1850s without ever straying from the central narrative.

As good a job as the author does in holding his focus and explaining Meigs, he never quite figures out Davis. It is difficult to cast any aspersions on him for that. It seems unlikely that even Davis could have given a complete answer to the question of why he would help build a monument to the republic’s greatness with one hand, while working with the other to destroy that greatness.

We’re probably better off just being thankful that he succeeded in the former and failed in the latter.