“If the Allies failed to secure the sea lines of communications (SLOCs) between North America and Great Britain from Hitler’s U-boats, the invasions of North Africa, Sicily, Normandy and even Southern France would not have been possible.” 

By Marc Liebman

WHEN ONE reads about the campaigns in Europe and the Pacific during World War Two, it’s common to come across references to the distances between point A and B. But rarely is it conveyed the real impact those many miles or kilometers had on generals’ or admirals’ overall strategy, tactics and the most important factor of all, logistics.

Distance and how materiel travels from the factory to the front is one of a war planner’s primary considerations. Without supplies, any campaign, brilliant as it may be, is doomed.

For example, while much is written about the invasion of Normandy being one of the most important battles of the Second World War, it would never have happened had the Canadian, British and American navies not won the Battle of the Atlantic, the longest and costliest campaign of the war in Europe.

Over the battle’s more than five-and-a-half years, the Allies lost 3,500 merchant ships, 175 warships and 741 aircraft, along with 36,200 Allied sailors and 36,000 merchant seamen. By contrast, Germany suffered 30,000 casualties, 783 subs and 47 other ships.

If the Allies failed to secure the sea lines of communications (SLOCs) between North America and Great Britain from Hitler’s U-boats, the invasions of North Africa, Sicily, Normandy and even Southern France would not have been possible.

To support these invasions, staggering volumes of men and materiel had to be shipped across the Atlantic – no small feat in wartime. Consider the following.   

A convoy steaming at six knots from New York to Liverpool would need 16 days and six hours to cover the 3,100 nautical miles between the two points. At a speed of 10 knots, that time drops to 13 days. A convoy leaving Norfolk for Gibraltar — a distance of 3,359 nautical miles — needed 17 days and 12 hours at six knots; 14 days at 10 knots. Heavy seas and storms could slow a convoy’s progress considerably and none of these transit times, even in calm weather, include the time and distance added from zig-zagging to avoid U-boat wolf packs.

Logisticians at SHAEF (Supreme Headquarters, Allied Expeditionary Force) also had to take attrition into consideration.

In 1940 and early 1941, U-boats were sinking as much as 25 per cent of the tankers and freighters in the convoys sailing from Canada to the U.K. For example, in September 1940, convoy HX-72 lost 11 of 43 ships. In October 1940, convoy SC-7 lost 20 of 35 ships and in December 1940, HX-90 lost 11 of 41.

These losses were unsustainable. If they continued, Great Britain would have had to capitulate for lack of food, fuel and raw materials to continue the war effort. Unless the Allies won the Battle of the Atlantic, there would be no victory in Europe.

Even with the sea lanes largely secured in the European war’s final year, moving ammunition and fuel to units at the tip of the Allied advance proved taxing.

One of the most publicized examples of supply shortages occurred in September 1944 when George S. Patton was ordered to halt his drive into Germany, even though he had the Wehrmacht on the run. Why? His Third Army was consuming fuel and ammunition faster than he could be transported across the English Channel and brought to the front. Eisenhower was constantly forced to choose between Patton and Montgomery when allocating his limited supply of fuel and ammunition. The Third Army’s halt came back to haunt the Allies in December 1944 when elements of the decimated German army that slipped away from Patton in the summer was reconstituted and resupplied for a massive counterattack through the Ardennes 

After the Second World War, Cold War military planners were equally focused on keeping Europe resupplied in the event of a contest between NATO and the Warsaw Pact. Winning what would be the Third Battle of the Atlantic (each of the two world wars had their own) would be critical to the Western alliance’s ability to fend off any conventional Pact onslaught into Europe. Just like Hitler’s Kriegsmarine, the Soviet Northern Fleet’s primary mission in any confrontation would have been to cut the North America SLOC to Europe. It remains the Russian strategy to this day.

The Pacific: A logistical nightmare

If moving men and materiel across the Atlantic seemed daunting in 1942, the challenges were even more acute in the Pacific War, where the distances were even more staggering.

Los Angeles and Honolulu are 2,231 nautical miles apart. That’s 11 days and 15 hours away for a ship moving at six knots. Increase to 10 knots and that time drops to nine days and seven hours. Yet, Honolulu is only 40 per cent of the distance between L.A and Tokyo. The two cities are separated by 5,600 miles of ocean. 

In early 1942, Pearl Harbor was the U.S. Pacific Fleet’s base of logistics. To move the vehicles, airplanes, men and materiel by sea to Brisbane, Australia, 4,116 nautical miles from Honolulu, the sailing time was 21 days, 11 hours at six knots and 17 days and four hours at 10.

L.A. to Australia, however, is 6,287 nautical miles. At six knots, the travel time is more than a month — 32 days and 18 hours. At 10 knots, the transit time drops to a mere 26 days and five hours. Considering that such a convoy would need another month to return to the U.S. to take on more supplies, a flotilla of merchant ships could make just six just round trips a year across the Pacific, and that’s not even counting loading and unloading times, maintenance and upkeep. 

In the Pacific theatre, convoys were needed to transport supplies to the South and Central Pacific. The U.S. to Australia/New Zealand route was vital for U.S. war plans. Fortunately for the Allies, the Japanese submarine fleet did not attempt to interdict supply convoys in the same way that the German wolfpacks did in the Atlantic. Instead, the Japanese used their subs as scouts. Later in the war, Japan used its own boats to secretly ferry supplies to stranded garrisons. Had the Imperial Japanese Navy conducted a campaign similar to the one that U.S. Navy submarines waged against Japan, the Allies would have faced a tougher Pacific War.

The U.S. however was aware of Japan’s dependency on imported raw materials and in early 1942, the Navy ordered its subs to starve the Japanese home islands of strategic resources. In fact, by 1944, America’s submarines were able to sink enough of the enemy merchant fleet to cut the flow of supplies to a trickle, something German U-Boats were unable to accomplish in the Atlantic.

Enter the supply ship shuttle

In order to keep more American ships and subs at sea and at the enemy’s throat —  and not having to return to port to refuel and resupply — American planners came up with some important, yet largely forgotten, innovations.

First, the Navy created forward bases where supplies could be stockpiled. Brisbane was one, Espiritu Santo in the New Hebrides (now Vanuatu) was another. From here, supply ships could rendezvous with task forces at sea that had retreated a “safe” distance from the Japanese.

Second, the U.S. Navy perfected underway replenishment (UNREP) in the early days of the war. Instead of ship’s steaming in trail connected only by a fuel hose, U.S. Navy ships steamed side-by-side so several hoses could be used to pump fuel from a tanker to the receiving ship. This made the process more efficient by reducing the refueling time.

If needed, an oiler could refuel four ships simultaneously — two on each side. Japan never advanced past the single hose, line astern method of refueling ships at sea. In fact, it was the method used to refuel the carrier fleet en route to raiding Pearl Harbor in 1941.

In addition to refueling, the U.S. Navy passed bombs, shells, food and other necessary supplies from supply ships to destroyers, cruisers, battleships, and carriers via cables linking the vessels in a process known as “high lining.” 

Small escort flattops, dubbed jeep carriers, were used to ferry replacement aircraft and aircrews to task forces, too. So with the shuttle of supply ships and UNREP as underway replenishment is now known, U.S. Navy ships were able to stay at sea for long periods of time and to some degree, minimize the effect of the Pacific’s long distances.

Guadalcanal and the threat to Pacific Strategy

Following the Japanese attack on Pearl Harbor, Tokyo ordered the seizure of islands across the western Pacific. These distant outposts would serve as a defensive perimeter for the Empire.

Commander of the U.S. Pacific Fleet, Admiral Chester Nimitz’s saw Japan’s building of an airfield on one of the islands in the Solomons — Guadalcanal — as a threat to America’s strategy.

Whether or not Japanese aircraft operating from the island could effectively interdict the U.S. to Australia convoys was not known at the time. However, the implication to the U.S. – Australia SLOC was clear and Nimitz ordered the invasion of Guadalcanal.

Operation Watchtower, the U.S.’s hastily planned assault on Guadalcanal took place on August 8, 1942. The tyranny of distance played a huge role in the campaign, which became a long-distance battle of attrition. The winner would be the one who could keep his troops and airplanes supplied. 

The nearest U.S. base to Gudalcanal – Espiritu Santo – was 1,000 nautical miles away and at the limit of the range of air transports. Brisbane lay 1,500 nautical miles away. Honolulu was 3,100 nautical miles to the east.

The U.S. Marine Corps has long held a grudge against the U.S. Navy for being driven from Guadalcanal before most of the First Marine Division’s supplies were unloaded. During the first few months of the campaign, few U.S. supply convoys reached the island and the Marines were always short of food, fuel, ammunition and medical supplies.

For the Japanese, conditions on Guadalcanal were far worse. American fighters and dive bombers operating from the now captured airbase, dubbed Henderson Field, prevented many of the IJN’s supply ships sprinting from Rabaul to Guadalcanal from delivering supplies. The island became known in Japanese circles as Starvation Island.

Britain and the Allied supply chain

In terms of area, the Battle of the Atlantic was a fraction of the size of the Pacific War. Allied armies fighting on the western front benefited from England’s well-developed ports, roads, railroads and a population willing and able to help.

Outside of Australia and New Zealand, the U.S. had to build the infrastructure it needed to support its forces operating in the vastness of the Pacific. In fact, America’s island-hopping strategy was driven by the need to secure new bases from which to continue the drive towards the Japanese Home Islands and final victory. The vast distances between these far-flung territories and logistics requirements to maintain the initiative drove how the U.S. prosecuted the Pacific War. After the U.S. captured Ulithi Atoll in the Caroline Islands, the U.S. Navy turned it into the largest naval base of the war.

As the war progressed, it became clear that the Japanese logistics capabilities to resupply their garrisons were not up to the task. The U.S. built bases on the captured islands where it could build up supplies and continue the attack. By doing so, the U.S. was able to mitigate the tyranny of distance and combined with better tactics, technology, airplanes, and ships, decisively defeat the Japanese.

 

Marc Liebman is a retired U.S. Navy Captain and Naval Aviator and the award-winning author of 14 novels, five of which were Amazon #1 Best Sellers. His latest is the counterterrorism thriller The Red Star of Death. Some of his best-known books are Big Mother 40, Forgotten, Moscow Airlift, Flight of the Pawnee, Insidious Dragon and Raider of the Scottish Coast. All are available on Amazon here.

A Vietnam and Desert Shield/Storm combat veteran, Liebman is a military historian and speaks on military history and current events.

Visit his website, marcliebman.com, for: past interviews, articles about helicopters, general aviation, weekly blog posts about the Revolutionary War era, as well as signed copies of his books.

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