The strategic bombing campaigns of the Second World War are even to this day a subject of historic controversy. With the Biltz on London, the Royal Air Force’s “thousand-bomber” assaults on German cities and the United States Army Air Force burning much of Tokyo to the ground in a single night of concerted attack as just a few examples, the effectiveness of the bombing campaigns has long been debated.
Part of this discussion revolves around ethical concerns and often whether the bombing campaigns in question should be ranked as war crimes. But another long running debate has been around the actual effectiveness of these offensives, and was the tremendous costs incurred in fielding vast fleets of bombers, massive numbers of specially trained personnel and the heavy losses they took really worth the results achieved. As one example, the Royal Air Force’s Bomber Command suffered over 55,000 crew killed in operations during the war, a loss rate of more than 44% of all RAF bomber crews that flew.
But interestingly, while the debate on the value of the various bombing campaigns will no doubt be one that historians discuss for as long as the Second World War is remembered, there was one such operation that was indisputably a massive success. And oddly enough, it is hardly remembered today, despite the fact that some contemporary participants believed that it rendered the need to either drop the atomic bombs on Hiroshima and Nagasaki or conduct an invasion on Japan itself unnecessary.
“Operation Starvation”, the aerial mining of Japanese waters in 1945.
Another odd factor with Operation Starvation is that it took so long for it to be implemented, as attempts to conduct aerial mining campaigns had been ongoing since the start of the War. In November 1939 the German’s began dropping magnetic mines in British waters, notably the Thames Estuary, and this led to a huge amount of effort by British scientists to develop anti-mine technology to protect shipping and to counter the threat.
Nor were the British ignorant to the idea; they had started working on air droppable magnetic mines in 1936.
And that effort was to prove remarkably successful compared to conventional attacks on German shipping. The British offensive aerial mining campaign in European waters began in April 1940, and over the next twenty months this effort sank or damaged 164 Axis ships with the loss of 94 aircraft. This might seem heavy until you compare it to the loss-to-kill ratio from air attacks on shipping in the same period; 105 vessels sunk or damaged for the loss of 373 British aircraft!
Certainly, the results impressed the British enough that they invested in a concerted aerial mining campaign in northern European waters, making up five percent of Bomber Command missions.
But here we get the first clues as to why the United States services were slower off the mark with a similar campaign against Japan. Because one of the advocates for the development and usage of aerial mines by the British was one Arthur Harris.
Better known for his advocacy of heavy bombers and mass attacks on enemy infrastructure, “Bomber” Harris had been one of the RAF officers in 1936 who had proposed the idea of magnetic air-dropped mines as part of a concerted strategic bombing campaign. With the outbreak of war and Harris being in senior leadership positions, ultimately becoming head of Bomber Command in February 1942, aerial minelaying always had serious backing with the British as part of the overall bombing campaign.
This support was notably absent in US military circles. Indeed, the possibility of mines being used offensively seems to have completely eluded both the US Navy and Army Air Force until well into the war, with advocates being a handful of scientists and junior officers. So, the first attempts to initiate an offensive mining campaign to disrupt Japanese shipping across their far-flung conquests didn’t really start until October 1942…with US Navy submarines.
This was rather successful and an important page in the history of the tremendous results that the American submarines achieved in inflicting huge losses to the Japanese mercantile fleet. But submarines were very limited in the amount of mines they could carry and, moreover, operating in shallow waters close to important and defended choke points that were the best place for mine laying was an extremely dangerous mission.
Aerial minelaying was a natural solution, but it took some serious proof of concept and poking from their allies to get the Americans to devote resources to any effort. The first aerial mining mission flown in the Pacific by the USAAF took place in February 1943 when ten B-24’s of the US Tenth Air Force based in India dropped forty British-supplied mines into the Irrawaddy near Rangoon in Burma.
Further south the Australian’s were also demonstrating the value of aerial mine laying, using Catalina flying boats to disrupt Japanese shipping all across the Southwest Pacific.
The results of this were impressive enough that Admiral Thomas Kinkaid, Commander of the US Seventh Fleet, wrote in an official communique in July 1944 that:
“Aerial mining operations were of the order of 100 times as destructive to the enemy as an equal number of bombing missions against land targets.”
The increasing numbers of advocates for mine warfare in the US services also found powerful support in the shape of Admiral Mountbatten, Supreme Allied Commander of the Southeast Asia Theatre. He lobbied General Hap Arnold for the new B-29s just then coming into service to be used in aerial mining in combination with efforts by British B-24s based in India.
The B-29’s, with their exceptional range, offered the prospect of being able to deliver mines even further than the long-legged B-24’s, and though many in the USAAF were dismissive of aerial mining, the amount of influence coming to bear meant that some effort had to be mounted.
On August 10, 1944, fourteen B-29s took off from Ceylon and dropped mines in the Moesi river leading to the oil refineries at Palembang, Sumatra, a target critical to the Japanese war effort. These mines sank or damaged seven ships and closed access for tankers to the terminals for a month, a huge disruption to Japanese fuel supplies.
This began a more concerted effort by the USAAF to conduct mining missions across the Pacific, though the amount of effort expended on aerial mining very much depending on the air commander in charge of the region’s attitude to the tactic.
As examples, the China-based 14th Air Force under Claire Chenault was an enthusiastic layer of mines, primarily in the Yangtze river, which played a major role in impeding Japanese logistics in the country. By contrast General George Kenney, commander of the Fifth Air Force operating in the Southwest Pacific, had no time for the concept, and his aircraft carried out just a single mining mission throughout the war.
To be fair, both theaters and commanders had different priorities, and for Kenney the RAAF was undertaking the aerial mining role in the Southwest Pacific anyway. But there was no denying as 1944 wore on that aerial mining could be extremely effective and that the Japanese, a nation and empire utterly reliant on its maritime trade to stay fighting, was potentially very exposed to a concerted mining effort.
Indeed, as the post war Strategic Bombing Survey put it:
“No major power in the world was more dependent upon ocean shipping than Japan.”
While to this point the efforts had been concentrated on what was dubbed Japan’s Outer Zone, with the capture of the Marianas Islands the USAAF now had the ability with its B-29s to attack the Japanese home islands directly. But even towards the end of 1944, the decision to commit to a dedicated aerial mining effort was still resisted by many in the Air Force, including the Commander of the USAAF, Hap Arnold.
The strategy envisaged for the bombardment of Japan called for a maximum effort in destroying war industry and land-based transport hubs, with mine laying very much a lower priority. But in November 1944 Admiral Nimitz threw his weight into the argument, calling for a proper campaign as part of a greater blockade of Japan that the US Navy was going to conduct.
Arnold gave way, partially, and agreed that the XXI Bomber Command, which was to conduct much of the bombing campaign on Japan, would carry out around 150 mining missions a month delivering up to 600 mines when the bombing campaign got into its stride in April 1945.
But this plan went out the window when the XXI got a new commander in January, a certain Curtis LeMay.
LeMay, who transferred from the afore-mentioned 14th Air Force in China, was convinced that the way the B-29 was operated over Japan was incorrect, leading to the low-level firebombing of Tokyo. But LeMay was also firmly convinced that aerial mines were an excellent weapon, and immediately ordered that the upcoming mining campaign fly more than three times the number of these missions than originally planned.
Thus, the seeds for Operation Starvation were laid. This would target the Japanese inner zone, directly intended to hit the critical shipping that served the Japanese home islands.
In February 1945 the 160 B-29’s of the 313th Bombardment Wing based on Tinian were ordered to begin training for the new campaign. The aircraft were modified to house AN/APQ-13 radar to allow dropping at night and in poor weather, and had changes made to their bomb bays so as to accommodate twelve 1,000lb Mk.26 mines or seven 2,000lb Mk.25’s. These could be fitted with magnetic, acoustic or pressure fuzes, making sweeping difficult for the Japanese.
The operation itself started in March 1945, with the first priority being to close the Kanmon Straits between Honshu and Kyushu.
This was an absolutely critical route that linked the Sea of Japan and the Inland Sea, providing the safest route between most of the major cities and production centers and the Japanese conquests in Korea and China. Between 27 March and April 12, the 313th dropped 2,030 mines in this narrow stretch, which led to the entire strait being closed for two weeks and even once reopened maritime traffic through this waterway was just a tenth of what it had been before the start of “Starvation”.
The next part of the operation targeted the key routes serving the main production centres, principally Tokyo, Kobe, Osaka and Nagoya.
This saw only two missions flown, one on the 3rd of May the second on the 5th, but by almost two hundred aircraft which dropped a total of 1,422 mainly Mk.25’s mines into the waters around these massive ports, jamming them solid with traffic that couldn’t leave or enter.
Phase three of the operation began on May 13 and saw minefields sown along the Northwest coast and around the Kanmon Straits again, further cutting Japan’s links to the Asian mainland and impeding coastal traffic. A total of 1,313 mines were laid for this throughout May, and losses for Japanese shipping began to escalate. In that month and in the Kanmon Strait alone some 113 ships were sunk, which was more than was destroyed in the same period by the celebrated submarine campaign being waged by the US Navy.
In June the 313th began targeting more of the northwest coastline and shipping routes, dropping 3,542 mines. Operation Starvation reached its crescendo in the following month, and between July 7 and August 14 another 3,746 mines were dropped by the B-29s.
These reinforced the existing minefields and also closed many of the Korean ports sending supplies to Japan.
August 15 saw Japan surrender, and Operation Starvation ended.
In terms of figures, it saw 1,529 aircraft sorties flown over 46 missions, which represented a mere 5.7% of the missions flown by the XXI Bomber Command. This saw 12,135 mines laid in a five-month period for the cost of 15 B-29s, which must rate as one of the lowest loss rates suffered by just about any air force operation flown during the entire war.
And for this, Operation Starvation was credited with sinking 670 ships with a combined total tonnage of 1,251,256 tons (p.33), more than all other methods in the same period combined.
The Japanese merchant fleet was thought to have about 2,000,000 tons of shipping available at the beginning of Starvation (p.33), so these losses were catastrophic for both Japanese war production and for suppling their remaining forces still fighting in the Pacific, southeast Asia and China.
Plus, the other factor that is hard to quantify but was of huge importance was that it wasn’t just the sheer numbers of sinkings that were taking place, but that ships simply couldn’t sail on the major supply routes to and from the critical Japanese supply and production hubs, often being bottled up in port, fearful of moving.
And in terms of the campaign’s effectiveness, we can look to the words of one of those whose job it was to try to combat it. As part of the post war Strategic Bombing Survey the Chief of the Mine Section of the Japanese Navy’s Technical Department, Captain Kyuzo Tamura, was extensively questioned about the effectiveness of the US mining campaign, his opinion on the ordnance involved and on Japanese countermeasures.
One question revolved around his assessment on if the United States had divided their efforts between mining and bombing correctly and whether an increased focus on mining earlier would have been more effective than the policy adopted.
“The result of B-29 mining was so effective against shipping that it eventually starved the country. I think you probably could have shortened the war by beginning earlier.”
This sentiment was echoed by a range of other Japanese officials and industrial magnates, who reported that Operation Starvation had essentially achieved its title, stopping Japan’s ability to fight effectively or even feed itself.
And that brings up the point made at the beginning of all this; why isn’t Operation Starvation remembered better?
Despite the huge success, it almost seems to be the unwelcome stepchild for some of the big names associated with it. As a RAND report written in 1974 about the campaign points out, Admiral King, Chief of Naval Operations for the US Navy during the War, doesn’t even bother to mention it in his memoirs, while “Hap” Arnold, who had personally been involved in forcing through the development of the B-29 and which could have arguably justified its creation on the success of Operation Starvation alone, gives the campaign two small paragraphs.
Perhaps mine warfare just wasn’t sexy enough? After all, dropping metal containers into the sea is hardly dramatic – no burning cities or vicious battles with defending interceptors to capture the imagination.
It is also hard to portray the real success of the operation; keeping ships bottled up in port and unable to do their seemingly dull but utterly vital job of trudging across the ocean, carrying all manner of things. No one is going to make movies about that.
But while the histories might not be that interested in Operation Starvation, the US military certainly remembered. In 1972, when the United States was trying to come up with a way to pressure the North Vietnamese at the negotiation table and to stymie their Easter Offensive against the South, mining the port of Haiphong from the air was to prove a critical step in achieving both these goals.
And while other big names associated with the Pacific War might have skimmed over the importance of Operation Starvation, Admiral Nimitz certainly recognized its value.
As he put it:
“The planning, operational, and technical execution of Twentieth Air Force aircraft mining on a scale never before attained, has accomplished phenomenal results and is a credit to all concerned.”