Integrating fictional characters with historical personages and real settings, and alternating sections of chapters between London and the Spanish front, Tillyard manages to curate a vast, detailed plot into a readable whole. Clearly her knowledge of the historical context was put to good use in the deployment of key details and various elements of the plot (in which a field doctor experiments with blood transfusions, and we witness the development of early gas lighting attempts and the beginnings of the Rothschild banking empire).
While it took me little while to get into the book, and I found myself drawn more to several of the minor characters than to the headliners of the novel, no real matter. It ended up being a good read, and I'll certainly watch for Tillyard's next (which I suspect may feature at least a few of the same cast).