A fine addition to the Osprey series, "Fortress." Here, the fortress at issue is the German fortification of the Rhine River. It began as the Westwall and became redesignated as the West-Stellung. The Westwall was operational early in the Second World War; it was, as the work terms it, a pale imitation of the opposing Maginot Line.
A useful way of comparing the Westwall with West-Stellung is a map on page 5. The Westwall was a narrow line; the West-Stellung was a defense in depth with fortifications stretching many miles in depth. The Germans begin work on the deeper defensive line as their fortunes began to decline on the Western front. The line was in place by 1944 through 1945. However, it was not as sturdily fortified as desired.
When Allied forces began to press against it, the soldiers defending the line were much degraded over what the German forces fielded earlier. The book describes the different places along the fortress and also considers how the line was actually defended. The book concludes by noting that (Page 60): "The value of the West-Stellung declined after the defeat of the Ardennes offensive, due in part to the drastic decline in the effectiveness of remaining German formations. . ."