I can understand that certain reviewers might consider this book - as well as other of Lincoln's works - "popular history," written for the masses, of no interest to the scholar. And perhaps their evaluation is correct - from a certain perspective, but one that I don't share.
I will concede that the organization and content of this book reminds me of other books that appear to be greatly expanded versions of lectures presented to undergraduates. If that's the case in this instance, then the undergraduates who heard Lincoln's lectures were extraordinarily fortunate students of history.
I write this because, in my estimation, "In War's Dark Shadow" is a "square one" book. It offers just the right material in an order, derived from the "latest" secondary works, i.e. works current as of the date of publication - rather than archival sources, that allows the attentive reader to form a sense and an understanding of an historical whole. Such a framework equips a reader - like me - to acquire, interpret and evaluate the content of articles/monographs that treat narrower topics. [I've written about "square one" books in other comments and responses I've recorded here. So I won't reiterate my thoughts now.]
And I will also say that Lincoln's complete command of language and narrative technique makes "In War's Dark Shadow" a thrill of a page-turner - just in this manner of all his books that I've read. Rendering this book a specimen of the very best sort of square-one book I can imagine.
So who might profit most from a careful and considered reading of this book?
Well, me - for one. Over the past eight to ten years or so I have read three of five narratives by Lincoln on late imperial/early Soviet history. Unfortunately I read them in reverse chronological order of their subjects - which is the order in which I first encountered them. When I leave the workforce and I have time and energy to devote to systematic reading and study of these subjects, I intend to read them in their proper order, which is: (1) "In the Vanguard of Reform," (2) "The Great Reforms," (3) "In War's Dark Shadow," (4) "Passage Through Armageddon," and (5) "Red Victory." At that point, I expect, I will have developed a net of rather fine mesh, as it were, that will allow me to read histories of narrower focus and more specialized content with more thoroughgoing comprehension and therefore longer recollection that I otherwise would/could.
I think I will read Figes' "A People's Tragedy" - a more recently completed square-one book - once more.
And this need arises because "square one" books (like Lincoln's and now Figes') can become outdated rather quickly. In the case of Lincoln's "In War's Dark Shadow" I have to believe that historians have created entire libraries of books on exactly his subjects since its publication in 1983. Indeed, the most recently published works that Lincoln lists in his bibliography of "Works Cited" date to 1980-81 - thirty-five years ago. But more recently published square-one books, such as Figes', don't necessarily supercede their predecessors. Progress in historiography - whatever that may mean - isn't inevitable. So I must read them all - again and again - until I designate a different set of such works as authoritative.
And besides, at my advanced age and in consideration of the daily, exponential expansion/extension in me of curiosity and interests, I can't even hope to retain even a minute portion of the information I ingest - if only for an hour or two. So I consult square-one books repeatedly - just as I would consult other handbooks and guides to any field of inquiry and study.