The initial operations of B-29 Superfortress bombers of the 20th Air Force against Japan were, for a variety of reasons, not nearly as successful as the Army Air Forces had hoped. The stupendous costs poured into building the B-29 fleet were compared to the meager returns of strategic bombing of industrial targets, and the math was bad. For one thing, the jet stream over Japan (and the higher operating altitude of the B-29 compared to B-17 and B-24 types) meant bombing accuracy was somewhat appalling.
These poor results were a major factor in the well known switch from daytime precision bombing to night incendiary attacks that razed Tokyo and so many other cities in the last months of the war.
One other mission the B-29s undertook is virtually forgotten today, but had an impact far out of proportion to the effort expended.
That mission was Operation Starvation, the offensive aerial mining campaign against the Japanese home waters.
A simple glance at a map shows that as an island chain, Japan is critically dependent on sea traffic to move supplies, people, and commodities. Further, virtually all of Japan’s strategic industries were almost wholly dependent on commodities that had to be imported from either the islands of the South West Pacific or from the Asian mainland. From almost the first day of the war, the US Navy had instituted an effort to deny the Japanese the use of these sea lane, primarily through its submarine force.
At the urging of ADM King, GEN Hap Arnold agreed to devote a small percentage of 20th Air Force missions to aerial mining.
Beginning on March 27, 1945, B-29s of the 313th Bombardment Wing would eventually fly 1,529 sorties in 46 missions, and lay 12,135 mines. That accounted for just under 6% of 20th AF sorties. In return, postwar survey would reveal that the mines accounted for an astonishing 670 vessels sunk or damaged, with a tonnage of 1.25 million tons. Considering the Japanese merchant fleet was estimated to have only about 2 million tons available when the campaign began, this was a stunning return on investment.
Additionally, in addition to direct losses, the minefields effectively forced Japan to cease shipping to many ports, and through many sealanes. Operation Starvation was aptly named. Japan was unable to feed itself from domestic crops alone, and by the end of the war, the mining, combined with the submarine force blockade, meant that food shortages in Japan were rapidly becoming critical. Whether such a blockade would have been enough to preclude the need for the atomic attacks has been hotly debated for years, but clearly offensive aerial mining was a potent weapon against those nations that relied on the sea for their survival.
All this at a cost of only 15 B-29s lost, less than a 1% loss rate.
The US would not forget the success of Operation Starvation. When the US began its involvement in the Vietnam War, virtually the first request of the Joint Chiefs of Staff to the Johnson White House was to allow the aerial mining of Haiphong Harbor. President Johnson declined.
Eventually, in 1967, President Johnson would authorize the aerial mining of several rivers in North Vietnam, and on the night of February 26, 1967, for the first time since World War II, and for the first time ever by jet, the US delivered aerial mines that effectively shut down traffic on those rivers.
For a more detailed analysis of aerial mining in World War II, and especially Operation Starvation, read the paper submitted below.