When modern times have seen political family dynasties like the Bushes and the Clintons, members are generally united against outside enemies. Not so those Roosevelts.

For while they produced two U.S. Presidents, a well-regarded do-gooder, and others who held offices in the government and the military, their intra-family backstabbing, score-settling, jockeying for position, power, wealth and jealousies seem ripped more from the story line of Westeros than Washington, D.C.

In this far-reaching, gripping and scandalous narrative, Mann takes apart the family dynamic over a century. And while it contains plenty of biographical details, the timeline leapfrogs through history.

Things start with the scorched-earth relationship between the future president, Theodore Roosevelt, and his brother Elliott. Growing up in a household where seemingly every mundane task was a contest of who could be smarter, faster or stronger (which Teddy would carry over to his own children, with mixed results), the brothers battled constantly.

But when the restless Teddy’s political, military and adventuresome life ascended, Elliott was happy as the bon vivant party boy who liked ladies and liquor in even keel. It’s been a long-held belief that Teddy was doing the “right thing” by trying to have Elliott declared insane and committed to an asylum.

But as Mann writes here, Teddy’s reasons had more to do with his own personal gains and self-satisfying moral compass that with his brother’s well-being.

When Elliott impregnated his chambermaid, the woman and her son were abandoned, promises of financial support never materializing. Yet Elliott Roosevelt Mann comes across as the most decent character in the book. His descendants were eventually welcomed into the family and officially recognized in more recent times, and this book is the first to reveal that branch of the family tree so firmly.

When the committal didn’t work legally, patriarch Teddy completely ostracized his brother, forcing him to live separately from his wife (whom he didn’t care much for and pecked away at) and their children, devastating all sides, none more so than Elliott’s young daughter, Eleanor, who doted on him and vice versa. Deciding to fully become the image, Elliott Roosevelt became a shell of a man, dying at the age of 34.

Teddy’s precocious daughter, Alice, was the nation’s “first teen idol.” She was also a “wild child” whose exploits of smoking, drinking and hanging around older men while partying into the wee hours became newspaper fodder – and an embarrassment to her father, sitting in the Oval Office steaming.

Her behavior was partially a rebellion against her place in the family as the only child of Teddy and his first wife, while his second wife, Edith, and their five children received the most love and attention.

Teddy’s fifth cousin once removed – Franklin Roosevelt – was making his own political waves after marrying Eleanor. And while regarded as a pampered effete by the Teddy/Oyster Bay Roosevelts, he further irked them by running as a Democrat.

And while their marriage/family life seemed at first to be solid, Franklin’s frequent absences, Eleanor’s own muted personality and quest for a wider purpose in life, and a very, very involved mother-in-law began to pull them apart.

Nevertheless, as both found emotional and physical companionship with others – with their own tacit approval and encouragement – Franklin and Eleanor epitomized an early “alternative family.” They would lead parallel existences.

Still, both politics and personal grudges were bloodsport – and not always enacted in private. “In times of stress,” Mann writes, “the fundamental Roosevelt characteristic was to tear each other to shreds.”

That might mean Eleanor openly campaigning against her cousin – Teddy Roosevelt Jr. for God’s sakes! – in a car outfitted as a teapot to remind voters of his (disproven) connection to the Teapot Dome Scandal. It might mean Teddy’s widow supporting FDR’s presidential opponent, Herbert Hoover, on election night. It might mean Alice using her newspaper column to skewer Franklin’s government. Alice, who would have one Congressman’s baby while married to another.

Add to that many more tales of infidelities, illegitimate children, business, suicide, scandals, exile, rebellion, alcoholism among both major Roosevelts and a slew of lesser-known sons, daughters, in-laws and offspring, and you’ve got a tale that puts to shame anything from medieval English times. Forget the War of the Roses.

Mann’s book is an incredible work of scholarship, but also reads like a ripping good multi-generational historical year. He says that 90 percent of his 1,300 notes are from primary sources, including letters, diaries, datebooks, court, military and FBI records, and more.

In the end, while dozens of Roosevelts appear in these pages, it’s Eleanor Roosevelt – who bridged the two presidential dynasties – who emerges as the central character. A great force whose decades of advancing progressive social, political, racial and sexual topics made the initially shy and awkward girl the most accomplished of the clan. And that is really saying something.

The Wars of the Roosevelts: The Ruthless Rise of America’s Greatest Political Family
By William J. Mann
624 pp.
$35
Harper