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After suffering dreadful losses in the North Atlantic, Bay of Biscay, and Gulf of Mexico in 1942 and 1943, the U-Boat arm of the German Kreigsmarine sought to field a submarine that was technically much more advanced than the Type VIIc. Eventually this resulted in the Type XXI submarine, with much greater battery capacity, a hull optimized for speed underwater, and much improved sensors. Technical and production issues meant that Nazi Germany was able to build 118 before the war ended, yet only four were actually ready for service. After the surrender, under the terms of the Potsdam agreement, the US, France, Britain and the Soviet Union all received examples of the Type XXI.

The Type XXI would greatly influence the US conversion of its Gato-class fleet boats to GUPPY configuration. Even more importantly, it showed that the WWII approach to ASW would likely be ineffective in the future. The US Navy had to presume that any future Soviet submarine designs would benefit from the Type XXI design (and boy did they).

The slow escort carriers and destroyer escorts of the Battle of the Atlantic, able to cope with submarines with a submerged speed of 3-5 knots would be hard pressed to defeat submarines with a submerged speed of up to 20 knots. Where a plane or destroyer escort that forced a Type VIIc to submerge effectively removed it from the fight, a Type XXI based submarine might easily evade the short ranged sensors of the day, and continue to press its attack, and even submerged, outrun the destroyer escort.

The US Navy, seeing the threat fast submarines posed to carrier task forces, gave considerable thought to what would be needed to counter such a threat. Various technical and operational imperatives drove the design of a ship specifically intended to counter fast submarines. First, the range of the sonar needed to be greatly improved. Long range sonar means lower frequency sonar, which in turn means a much larger sonar transducer (and its associated sonar dome). Further, the deeper such a transducer is submerged, the better it performs. Both those considerations called for a significantly larger escort than the destroyer escorts, or even the fleet destroyers of World War II. The high speed of the Type XXI and its derivatives also called for a very fast escort, one that could maintain high speeds even in a high sea state. This again called for a larger ship.

While the primary mission of this hypothetical escort would be anti-submarine warfare, it would also need to be able to contribute to the air defense of the task force. Here though, it’s primary “weapon” would be its ability to act as a fighter director. This called for an extensive radar suite, and a spacious Combat Information Center. Again, that requirement argued for a larger ship. Since a task force’s primary anti-ship weapon was seen as the aircraft of the task force, the escort would not need a major caliber gun system. Instead, its guns would serve as its secondary anti-aircraft weapons. But it needed a high rate of fire, which meant several mounts of a high rate of fire gun, in this case, the 3”/70 twin mount. Again, multiple mounts drove the size up.

Given that the Navy had several hundred ships in reserve after World War II, finding the money to build new ones was very much a challenge. Still, the Navy begged enough money from Congress to lay down a prototype of the new anti-submarine hunter. Originally designated the CLK-1 (Cruiser, Hunter-Killer), while she was cruiser sized, she was built to destroyer standards for cost reasons, and was soon redesignated DL-1, for Destroyer Leader. Christened the USS Norfolk, and commissioned in 1953, she was less than a resounding success.

She was a big ship, some 540’ long, and displacing 5600 tons. Her 3”/70 mounts weren’t ready when she was commissioned, so her first battery was the regular 3”/50 guns. Later, when the 3”/70s were installed, they turned out to be maintenance nightmares, and not terribly effective at that. Other weapons included Weapon Alfa, with four mounts for the rocket thrown depth charge. Weapon Alfa likewise was a maintenance hog. Eventually in 1960, the excellent ASROC was added, finally giving the Norfolk an effective ASW standoff weapon able to capitalize on the excellent SQS-23 sonar.

USS Norfolk spent most of her career serving as a test bed for new weapons and systems, and as a laboratory for trying out new techniques and tactics. Her design was clearly far too expensive to build in numbers as a specialized ASW escort.

Nonetheless, she did inspire the follow-on Mitscher (DL-2, latter DDG-35) fast carrier task force escorts, and a series of other large destroyer leader types. Those classes had a primary focus on anti-air warfare, but still retained a significant ASW capability. The Navy was never able to afford as many of these large, fast escorts as it needed, but these later classes would serve as the linchpin of a task force screen until their replacement by the Ticonderoga class Aegis cruisers in the early 1980s.