Oliver Cromwell and King Charles II. Ulysses S. Grant and Robert E. Lee. Wars — drawn-out, blood-drenched civil wars — sometimes boil down to two figures who personify the conflict, on whose shoulders rests the will to fight. In "A Rope From the Sky," Zach Vertin's panoramic, absorbing account of South Sudan's turbulent creation, Salva Kiir, the president, and Riek Machar, his vice president, loom large. From opposing tribes, the Dinkas and the Nuers, they severed their political partnership in an orgy of killing and retaliation, almost severing the neck of the young republic.

After decades of internal strife and famine, Sudan, a rich gumbo of ethnicities and creeds, had exhausted itself. A 2005 cease-fire allowed Southern states six years to decide on separation, a delicate peace brokered by the charismatic John Garang, South Sudan's George Washington, who perished in a helicopter crash that same summer, a likely assassination.

Tensions played out over the South's valuable oil fields: "The peace accord's wealth-sharing provision changed everything: Oil wasn't a major source of revenue for South Sudan's economy; it was the economy … the goat herder and his wife remained illiterate, and their children had no primary school to attend. But the children of … elites wore designer clothing and drove Range Rovers to premier schools in upscale London neighborhoods and leafy Nairobi suburbs."

After the peoples of South Sudan overwhelmingly voted for independence in 2011, many observers assumed that this impoverished country would grow and that the oil money would trickle down. Foreign aid poured in. The capital of Juba, previously a cluster of modest buildings and dirt roads along the White Nile, spread out in layers. But governmental corruption was rampant, what Vertin describes as the "schizophrenic incoherence of Salva's government."

The old ethnic wounds rubbed raw. A series of horrific massacres unfolded in December 2013, when Salva, donning his trademark black cowboy hat (a gift from President George W. Bush), targeted Riek, the "rebel with a Ph.D." The bloodshed escalated, prompting the international community to try to save the failing state.

"A Rope From the Sky" — the title refers to a Sudanese folk tale — is a masterful account of the birth and near-death of a nation. Minnesota native Vertin, a seasoned diplomat and journalist active in Sudan for decades, offers a wealth of "you are there" reportage and revelatory interviews with South Sudan's founding fathers. He seams together a staggeringly complicated puzzle, re-creating the savage street battles and high-level diplomacy that has informed South Sudan's infancy and childhood.

But much of the book's texture comes from beautiful portraits of the South Sudanese people, as they carve out lives in thatch-roofed tukuls in the bush and in Juba's electronic shops and open-air markets.

"A Rope From the Sky" is an invaluable contribution to the literature of global politics, an intimate diary of a young nation's tenuous struggle to survive, and a cautionary tale of two men whose personal animus pushed their country to the brink.

Hamilton Cain is the author of "This Boy's Faith: Notes From a Southern Baptist Upbringing," and a member of the National Book Critics Circle.

A Rope From the Sky
By: Zach Vertin.
Publisher: Pegasus, 497 pages, $29.95.
Event: In conversation with Mary T. Curtin, 7 p.m. Jan. 25, Magers & Quinn, 3038 Hennepin Av. S., Mpls.