Army At Dawn
A thorough and thoroughly-readable account of the War in North Africa. In the years before World War II, the US Army was a small and inconsequential force; in 1942, it became a large but still largely-amateur army. North Africa became "a place to be lousy." But though it was a sideshow, it was important as more than practice for Normandy; the Germans lost half as many troops in Africa as they did at Stalingrad.
Atkinson is so readable that he hides his erudition; only after finishing the book and thumbing through the notes and sources did I see exactly how much research he did, and how thorough that research was. Atkinson works heavily from primary sources and contemporary records, but is such a fine storyteller that you'd never know this isn't just popular history.