H.W. Brands is not a historian who focuses on one genre of history.

He’s more of the David McCullough school of history’s breadth rather than the Joseph J. Ellis school that focuses on one historical era.

Brands has written biographies on Theodore Roosevelt (“T.R.”), Benjamin Franklin (“The First American”), and “Andrew Jackson” and histories such as “The Reckless Decade,” “The Age of Gold” and “Lone Star Nation.”

Come May, his newest, “Reagan: The Life,” is scheduled for publication.

In 2008, Brands focused his studies on a towering figure of the Depression era and World War II. “Traitor to His Class: The Privileged Life and Radical Presidency of Franklin Delano Roosevelt” is a massive look at the nation’s longest serving president and arguably one of its greatest.

Brands spends little of this book on FDR’s childhood and youth. The historian relatively breezes through Roosevelt’s pre-presidential life. Within less than a few hundred pages of this 800-plus-page volume, Roosevelt has entered the presidency.

Brands focuses on the details of Franklin and his administration: The Hundred Days, the New Deal, the Great Depression’s ebb and flow, the precedent-shattering nominations and new presidential terms, the Lend-Lease programs to Great Britain’s stand against Nazi Germany, the Japanese attack on Pearl Harbor, the entry into World War II, the friendship with Britain’s Winston Churchill, the alliance with Russia’s Josef Stalin, the restructuring of Allied world power even as the war continued, the formula for the Cold War to follow, FDR’s passing shortly before the war’s conclusion.

Brands includes all of these events and the personal reactions to them, but he sticks with the book’s title theme. Roosevelt was born into wealth and class but defied his upbringing to pursue liberal programs to aid the poor, the working man, the unemployed.

Brands also seems to have a fly-on-the-wall perspective on FDR’s many off-the-record talks with the press. These interludes reveal the political Roosevelt at work.

“Traitor to His Class” is an informative and insightful read.