Convoying past Somalia not a panacea

I linked yesterday to an op-ed in OpinionJournal urging merchant vessels transiting the waters off Somalia sail in convoys, escorted by warships. The piece is worth reading, but author Peter Zimmerman misstates why convoying was done during World War II's Battle of the Atlantic. He writes that the same convoying "tactic which defeated the U-boats can put an end to the majority of pirate attacks."

Problem is, convoying did not defeat the U-boats. Convoys, large numbers of ship sailing together under a unified command, had been devised in World War I as a defense against U-boats. Convoys' advantage lay solely in the fact that the Atlantic is so enormous that a convoy of even dozens of ships was not really easier for a U-boat to find than a single vessel. Besides, there would never be enough destroyers or corvettes to escort single vessels. Convoys grew in size as the war continued. Only very fast ships such as Queen Mary were permitted to cross the sea alone, on the supposition that they were fast enough to outrun any U-boat that might detect them (which proved correct).

In June 1940 Admiral Doenitz devised a new tactic for his boats. He called it Rudeltaktik, or "pack tactic," which the Allies called "wolfpack." Doenitz ordered submarines to patrol in lines to look for convoys. When a U-boat discovered a convoy, it would shadow it and report its speed and heading to "Admiral U-boats," as Doenitz's headquarters was known to U-boat crews. Admiral U-boats would then signal boats in reasonable range to converge on the convoy and make a coordinated attack.

This tactical innovation devastated convoys. Wolfpacks varied in size from only a few U-boats to 20 and sometimes more. Convoy ONS-5, for example, was attacked by a wolfpack that finally amounted to 55 U-boats in April 1943 in a convoy battle lasting two weeks. ONS-5 lost 13 ships totaling just under 62,000 tons. The month before, 43 U-boats sank 93,500 tons of convoy HX-229. These convoy battles were not hit and run affairs. They usually lasted many days, often more than a week. March 1943 was the worst month of the war for the Allies, with more than a million tons sent to the ocean floor.

Yet within two months, the U-boats began to suffer accelerated losses and lose the battle. Four big developments defeated the U-boats:

1. Signals intelligence and British codebreakers, who enabled Allied navy commanders to intercept and read orders to U-boats at practically the same time as the German commanders.

2. Improved technology in submarine detection, especially aircraft-borne radar and "huff-duff," or High Frequency Direction Finding radio receivers.

3. Improved anti-submarine weapons and weapons-employment technology, especially the mass introduction of small corvettes, a purpose-designed ASW craft.

4. "Intentional lethality" - the change of martial attitude of British commanders from neutralizing U-boats' ability to attack convoys to the determination to sink the U-boats. (Americans mostly followed the British lead in ASW.) In this tactical change, aircraft became the key players. German U-boat survivors (they suffered a 75 percent casualty rate) agreed that aircraft were their greatest threat, and none more so than the long-range, heavily-armed B-24 Liberator bomber.

I wrote in detail about the ASW campaign in the north Atlantic back in 2006.

As you can see, convoying was only one tool in the Allies' drawer. It was important but by no means decisive. Moreover, German commanders devised tactics of their own that gravely threatened convoys and had great success in attacking them in U-boat packs, though they came to pay a terrible price.

So convoying past Somalia may be a good idea, but it won't necessarily be a panacea to ward off pirate attacks. Unlike the Atlantic, convoys will not be hard to find at all. The larger the convoy, the greater the number of escort vessels needed to secure it. Since the powers patrolling the waters now are unlikely to increase the number of warships by much, escorting convoys may increase vulnerability of single ships, whose sailings will still be in the majority.

Just as the German commanders adjusted to allied convoying, so will Somali pirates. If pirates adopt pack tactics as the U-boats did, they will likely successfully seize merchant vessels despite the presence of armed escorts. Ships in convoy must keep station, they can't maneuver to escape. Attacks from three or four points on the compass will be very difficult to counter. And if the pirates manage to seize only one or two ships per convoy, they will win.

(We do have a great advantage that our WW2 predecessors did not, though, and that is helicopters and UAVs. Today as then, aircraft will prove decisive in protecting convoys. The responsiveness of helicopters and UAVs and the fact that many men-o-war already carry them gives us a huge leg up in countering pirates. This would be especially true in escorting convoys.)

Convoying ships without the determination to use force to repel pirates attacking them is no solution, unfortunately. The Germans, at war with their strong martial tradition, pressed on despite high losses. Will pirates be as determined in the face of lethal opposition? Let's hope not.

Related posts.