We March Against England: Operation Sea Lion, 1940–41, 1940–41, by Robert Forczyk, Osprey Publishing, Oxford, United Kingdom, 2016, $30

World War II histories have long floated the proposition that Operation Sea Lion—the planned but indefinitely postponed amphibious invasion of the United Kingdom—represented the Third Reich’s first defeat. Beaten back during the Battle of Britain by the intrepid pilots of the Royal Air Force, the Luftwaffe never gained the required air supremacy, thus rendering Sea Lion impossible.

That narrative first came under scrutiny in the 1950s, as historians questioned whether the German invasion was a credible threat or merely a bluff meant to intimidate Britain into accepting a negotiated peace. Forczyk rejects such revisionism and provides compelling evidence of just how precarious the British position was before Sept. 15, 1940.

Instead of separating the 1940 Battle of Britain, the 1940–41 Blitz and the 1939–1945 Battle of the Atlantic into autonomous events, Forcyzk argues that at critical moments Germany had the ability to break Britain through a collective effort via a much larger air and sea campaign in conjunction with diplomatic efforts. While Forczyk provides refreshing analysis of a well-plumbed topic, he misses the mark by failing to accurately depict the fierce resistance of the RAF. He also neglects to mention that Fighter Command withdrew its bases beyond effective escort range, thus forcing the Luftwaffe to resort to night attacks on ports and cities, hoping to draw out the Spitfires and Hurricanes. By the end of the Battle of Britain the clash had moved from a tactical bid to secure air superiority to nothing more than an attempt to force peace by breaking British morale. The Germans ultimately failed to cow Britain, a fact Forczyk fails to address.

With the U.S. entry into the war Britain’s survival was all but ensured, even if all of its own offensive and defensive capabilities were exhausted or destroyed. That might not have been the case had those “few” not defeated the Luftwaffe. Forczyk insufficiently delineates a compelling “what if” scenario. Claiming no intent to present a conjectural history, he ends up weaving a narrative suggestive of the very thing he attempts to avoid.