(from my personal reading journal, Feb. 14, 2024)
I love a focused microhistory, and if Millard's catalog of bombastically-titled bestsellers are to be considered, the genre has some absolute bangers. River of the Gods focuses not, as I first assumed, on the overall European obsession with the Mile, but on the very tail end of that obsession, particularly the 1856-1860 journey to Lake Tanganyika, its precipitating events, and the fallout in the lives of those who undertook the journey.
The expedition was headed by orientalist, polyglot, and pervert Richard Burton, and he brought along notables John Speke, who went on to see the lake Victoria Nyanza (the "actual" Nile source until around 2006) and stole Burton's glory; and Sidi Mubarak Bombay, a waYao man sold into slavery in India who later became the best-traveled man in Africa. the journey was harrowing to say the least, and wasn't entirely fruitful in the end (the Akagera river is a more remote source, identified in 1950), but was a great geographic boon for Western understanding at the time.
I appreciated Millard's handling of the uncomfortable questions a modern reader would have for such a tale--what about the imperialism? the African guides?--and found her exploration of Speke's role in the ideologic background of the Rwandan genocide of 1994 fascinating. It turns out that the explorers of the time largely knew the value of native guides and their expert knowledge (even if the held proto-eugenic beliefs about them), but the heads of society back in the West felt differently, and their influence became the prevailing ideal.
Overall, quite interesting. I'd like to learn more about this era of history, fraught as it was, and would like to read more of her previous books.

As European interest in Africa and its wealth of resources increased during the 19th century, so too did the number of ill-advised white men setting off to try and map its interior. And the greatest and most difficult of these missions was to definitively discover the source of the Nile river.

This is a story with two rather unbelievable leads, only one of whom I'd heard of and then very vaguely. A book can't go wrong following such screwed up, pompous individuals like Burton and Speke, especially when we get almost as a foil the wonderful Sidi Mubarak Bombay. I thought the author did a great job showing both the positive and negative qualities of Burton and Speke, and both the incredible feat of their explorations as well as how their imperialist and racist views both contributed to and clashed with all they did.

However, I did think the story got somewhat disjointed, weaving away to discuss such topics as Burton's marriage which while interesting felt like it served to pad the page count. Burton and Speke's various Nile expeditions were only a slice of their lives, and I think the author had trouble working out how closely she must cleave to that central story, and how much else of their lives she must leave out, which made for meandering reading at times.

Curiosity, bravery, greed, pride and ambition brought these two men to the heights of fame and the pit of infamy. Speke, the Burtons, and Bombay come across as imperfect people in a perfect storm of exploration, politics, and colonialism. 

Even if you argued this text is biased in favor of Burton, I think Speke would have been a incredibly poisonous person to know. 

Additionally, if Sidi Mubarak Bombay is the true center of this story as is hinted at — the summary of his life, apart from Burton and Speke, should have earned a chapter of its own, as they received. And not tucked into the epilogue. Arguably, he did go further and see more then either, so the content was there.