Stegemann received his PhD in 1968 at the Free University Berlin with a dissertation on the German naval policy of 1916–1918, also published as a book; his scientific advisor had been historian Walter Bußmann [de].
Historian Dennis Showalter calls the chapter dedicated to the Battle of Britain "excellent", noting that Stegemann and co-author Klaus A. Maier [de] make a convincing case that the German defeat "rendered the spectacular continental victories of 1940 ultimately sterile".
In Volume III, Stegmann analysed the North Africa campaign, bringing into focus "the subtext on the operational risks of waging war on a shoestring".
[3] Historian Mark Mazower called Volume III "definitive" and praised it for its "range and intellectual energy".
He notes that the authors are widely read on the topics and are familiar with the existing controversies in the field, expertly guiding the reader through them.