I've read that once the German army started fighting a predominantly defensive war, armoured vehicles like the Elefant, Jagdtiger, Tiger B, and even smaller/more commonplace vehicles were very often used in static, camouflaged defensive positions.
Given the constant mechanical failures, the logistical/mechanical/battlefield support required to maintain and protect these tanks, and the huge amount of material/labour required, why build them at all? It seems like AT guns/PaKs would be more useful defensively, cheaper to make, and don't run out of fuel. Was the ability to move the gun at a speed not much faster than running really enough to justify making these things?
Thanks in advance!
The earlier, smaller, lighter anti-tank guns were able to be maneuvered into position, fired, and withdrawn by their crews. The 5cm PaK 38 was made with light alloys for exactly this purpose. However, the 5cm round proved inadequate. It's replacement, the 7.5cm PaK 40, was heavier, not only because of the larger gun, but the lighter materials were required for aircraft production. It required a prime mover to go very far. This made it very vulnerable once it's position was discovered. Self-propelled guns could fire and withdraw very quickly. The towed guns were also very vulnerable to artillery fire.
US forces had the same problem with the 3-inch M5 anti-tank gun that equipped about half of the tank destroyer battalions (ironically, many of those battalions had been converted back to towed guns after the poor showing of the half-track mounted M3 75mm GMC and the truck-mounted M6 37mm GMC in North Africa). At the Battle of the Bulge, in particular, towed TD battalions had to abandon many guns due to difficulties withdrawing them after engaging the enemy. By the tail end of the war, most towed TD battalions had traded in their guns for 76mm M18's or 90mm M36's.
Yeide, Harry, The Tank Killers: A History of America's World War II Tank Destroyer Force