In Nelson's Wake: A History of the Navy in the Napoleonic Wars 1803-1815 by James Davy. This is a general analysis of the British navy in the time period. It covers military, social and political roles of the navy in the period. Some of its parts explore less covered theatres and events in the Napoleonic Wars such as prisoners of war and the naval war in more obscure places like the Adriatic or the Indian Ocean. It is easy to understand and is good for both novices and experienced Napoleonic historians alike as it offers some interesting viewpoints and obscure information such as statistics on the British and French economies and individuals who are largely forgotten by most people.
The Forgotten War Against Napoleon: Conflict in the Mediterranean 1793-1815 by Gareth Glover. The title of the book pretty much says what it is. Admittedly I haven't finished it just yet however it is well written, some casualty statistics for certain battles conflict with other sources however it is, so far a decent study of the theatre in the Mediterranean.
Royal Navy: 1793-1815 and the Nile 1798: Nelson's First Great Victory by Gregory Fremont-Barnes. The Nile book is one of the best books on the campaign I could find along with Oliver Warner's book on it. It is relatively short at just 98 pages so if you don't have time for a 300-400 page book or just want to read on the Nile campaign this is a good book.
The First World War by John Keegan A great single volume account of the Great War.
- The Third reich Trilogy, by Richard J. Evans (consisting of the titles: "the coming of the Third reich, The Third reich in Power, The Third reich at War): A brilliant overview of the history of Nazy Germany, going back to the very first influences for Nazism until the fall of Hitler. Well written and very clear
- Battle cry of Freedom, James McPherson: a perfectly detailed one-volume history of the American civil War and it's causesIt's main strength is that it actually spends a lot of time explaining the economic reasons and situations that lead up to the war, instead of just limiting itself to the war itself
- 1776, David McCullough: this one was recommended to me by TJAdams, a valued member of this forum who is now sadly deceased. A very good overview of the American War of Independence; It might not be the best read if you know already a lot about the subject, but it provides a very good starting point on the subject.
- The War of Wars: the Great European Conflict 1793-1815, by Robert Harvey: A well written overview of the Napoleonic era, written in a non-pedantic and engaging way.
Aurelian and the Third Century by Alaric Watson is a fascinating and fairly short book about the Roman Empire in the 260s and 270s, a time of troubles. It is about the military, political and economic crises of the period, and how the emperor Aurelian, an officer-turned-emperor, sought to fix the empire's problems with great energy, originality and military skill.
You might compare with "The Fate of Rome", a recent book which considers the latest evidence on health and disease during the whole period of the Roman and Byzantine empires; it focuses on repeated, serious, depopulating, plague epidemics.