Operation Gi: The Japanese Attack on Yontan Airbase Okinawa
The surprise Japanese response to the firebombing of its cities
On the evening of May 24,1945, twelve Ki-21 Mitsubishi “Sally” bombers lifted off from an airbase in Kengun, Japan. They were on a one-way mission to defeat the American B-29 bombers that had been wreaking destruction on Japanese cities for months. Onboard were 136 elite, heavily-armed, and well trained commandos that were willing to sacrifice their lives to stop the American rain of terror from above.
As the war in the Pacific in late 1944 continued to gain momentum for America with more setbacks for the Japanese military, the Imperial Japanese Army became desperate to thwart the increasingly destructive B-29 raids that were decimating industry and its cities.
A branch of the Army, the Kempetai (military police) along with the Japanese Army Intelligence unit hatched a plan among the most audacious ever undertaken by a military unit.
The Japanese Army was forced to recognize the ineffectiveness of their anti-aircraft and fighter interceptors to blunt the impact of the increasing American B-29 raids.
The B-29 Superfortress
The B-29’s featured the first pressurized cabin of any WWII aircraft, and it was able to fly at 30,000 feet at 350 mph well beyond the reach of most Japanese fighters. It could deliver up to 20,000 lbs of bombs to targets 3,250 miles (roundtrip) away. The B-29 was America’s superweapon in the Pacific theater with a development cost that would surpass the Manhattan project.
How could Japan defeat such an advanced weapon?
The Geritsu Kuteitai
In November of 1944 the Kempetai called for the creation of the the Geritsu Kuteitai (Heroic Paratrooper) commando unit. The unit was created to employ direct action commando attacks on B-29 airfields in the Pacific. It was formed from the ranks of highly trained paratroopers and combat engineers who had extensive training in sabotage and demolition.
Japan had seen some success with kamikaze operations in the Philipines and around Okinawa. The Japanese high command started to think the only way to strike back at the Americans was with dedicated commando units that would sell their lives dearly for the emperor and take as many Americans with them as possible.
The Army selected Captain Michiro Okuyama to lead the group. He had extensive combat experience and well respected by his superiors. Okuyama was tasked with selecting 126 men for a one-way suicide assault mission. None were expected to return alive.
By December 5, 1944 the Geritsu Airborne Unit was assembled, with the addition of ten intelligence officers, they began training in earnest for their mission.
The unit was based at the Army Air Academy’s base at Saitama, Japan. At the academy, several mock up B-29’s were constructed for practice. Since the planes were relatively tall (29 feet) some new innovative devices were invented to expediate the destruction of the aircraft on the ground.
The first device was a 2 kg explosive charge with a large suction cup designed at the end of a long pole. The plan called for a commando to reach up with the pole attach the charge to the wing, and pull a landyard cord to activate a delayed fuse. The charge would explode, destroying the area at the point of attachment. It could also be used to attach to the fuselage of the plane. A hole in the fuselage of a pressurized aircraft would render it unusable.
The second device was a chain charge. It was a rope-like chain that was fitted with explosives along its entire 16 foot length. A small weight was attached to the end of the chain to facilitate throwing it over the wing of a B-29. When the charge was ignited it would sever the wing of the aircraft disabling it.
These were not stand off devices. They would require the commando to get right up to the aircraft to deliver the weapon system. In order to transport the commandos, an airlift unit was formed to move them into position and deliver them by belly landing their planes directly on US airstrips.
In early 1945 training ramped up with the commandos intensely training night after night until they became well versed with the workings of their new equipment and rehearsed with their assault tactics.
The initial plan
The inital plan for the Geritsu unit in January 1945 was to first attack the US bases in the Mariana Island group. Guam, Saipan and Tinian were all home to hundreds of B-29’s that were attacking and destroying Japanese cities seemingly at will.
The Geritsu Airborne unit was set to settle the score and destroy and disable as many US planes as possible. Captain Okuyama tasked each man with destroying three aircraft before attacking the crew and aircraft support facilities.
The Ki-21 bombers had limited range and would need to refuel to make the one way trip to the Marianas. That refueling point was to be the island of Iwo Jima. It was also the island from which the Japanese had been staging bombing raids on Marianas.
Unfortunately for the Japanese, Iwo Jima was the next US target in in the continued march across the Pacific to defeat Japan.
In January and early February, US air attacks on the Iwo Jima airfields intensified in preparation for invasion of the island. With the lack of a refueling stop, the Japanese mission to attack the Marianas airbases was canceled.
Operation Gi
In the Spring of 1945, Japan sustained devastating B-29 raids and continued to lose valuable island bases including Iwo Jima in March, 1945.
Once the US attacked and invaded the island of Okinawa in April of 1945, just 480 miles from the home islands, Operation Gi was put into place.
The Japanese high command had launched kamikaze missions to counter attack the US Okinawan invasion with limited success. Fighters from the US carrier groups offshore combined with the US Army and Marine fighters from the newly captured bases on the island were effectively shooting down over 60% of the Japanese planes that were launched.
Operation Gi was to be the action that destroyed the US fighter and bomber force on the ground. This was to be the opening action followed the next day by a blizzard of kamikaze flights designed to decimate and destroy the American Fleet. The US Navy was lingering in the Okinawa area in support of the ground action. If Operation Gi was successful the US ships would be exposed without their Okinawa based fighter support.
The design of the plan was relatively straight forward. The Imperial Japanese Army would send in a diversionary attack of several waves of bombers just prior to the arrival of the Geritsu planes. The diversion would cause confusion among the American defenders and direct their antiaircraft fire on high flying planes while the Geristsu group would sweep in at 150 feet off the ground. The Geritsu planes would approach unmolested and land on the Kadena and Yontan airbases disembarking their commandos who would immediately attack. The Imperial general staff believed the operation would defeat of the US invasion force in Okinawa.
The attack
On May 24, 1945 after a rousing short ceremony and two toasts, the group of Geritsu paratroopers bid each other luck and boarded their planes for the four hour flight to Okinawa. Each plane held twelve commandos and addtional flight crew. The force was divided into two groups: Force One consisting of eight planes would head to Yontan and Force Two with four planes would land at Kadena.
Each plane was specially modified with all defensive armament removed and painted in camoflage to reduce their visibility. Their flight crews were also armed with automatic weapons and grenades as well as mortars, to fight beside their commando comrades until the end.
As fate would have it, four planes developed engine trouble soon after take off and had to return to base. It was well known in 1945 that Japan suffered from scarcity of high octane aviation gas and it was often doctored and stretched with a variety of additives that could cause engine failures or spark plug fouling.
Nevertheless, the amended plan called for the remaining eight planes to continue on course to attack Yontan airbase at around 10:30 PM just after the diversionary attack by IJN and IJA bombers.
While the attack by the conventional Japanese bombers did not cause significant damage to the airbase, it did create a large fire. A full moon addtionally illuminated the airstrip for miles.
The American gunners who had just knocked down eleven bombers from the diversionary attack were alert for any continued attacks. The lull between the first waves of bombers and the arrival of the Geritsu planes gave them time to rearm and reaim.
With the use of ground and ship based radar (the US Navy had a ring of radar equipped destroyers up to 100 miles away from Okinawa to warn of inbound flights of Japanese planes) the Americans spotted some of the Geristu planes as they transitioned from flight altitude to their attack altitude of 150 feet. Night fighters were vectored out to meet the planes and were able to intercept and shoot down four of the bombers.
The remaining four planes continued on their trajectory to Yontan and were detected by American anti aircraft batteries protecting the airbase. Their slow speed and glide path made them easy targets and three of the planes were hit on the way into the airfield. The pilots of these planes crash landed their planes into the periphery of the runway and tried to turn their craft into giant kamikzes. A signficant number of the commandos survived the crashes and emerged from the wreckage firing their automatic weapons and attacking aircraft parked on the apron.
One of the Geritsu aircraft tail # 546 landed on the runway as planned and in hail of sparks skidded to a halt about 80 yards from the main control tower.
Immediately upon stopping, the Perspex glass nose cone of the plane popped open and out crawled several Japanese troops wearing blacked uniforms and firing automatic weapons. Once the Americans guarding the base realized there were Japanese troops on the ground, a melee erupted with wild firing in all directions. According to eye witnesses in the control tower, a group of Japanese soldiers gathered together as in a football huddle and then dispersed with sachel and other charges. They proceeded to blow up aircraft around them. They were soon joined by other Japanese commandos from the periphery of the runway as they ran from aircraft to aircraft firing their weapons.
The firefight lasted the entire night. At dawn a Marine unit was brought in to hunt down the last remaining commandos. At 12:55 PM the last commando was killed by the Marines.
The Keritsu unit managed to destroy four Corsair fighters, two PB4Y patrol bombers, four C-47 Dakota transports, and damaged 22 Corsairs, three Hellcat fighters, two PB4Y’s and two C-47’s. They also set the main fuel tank for the airbase containing over 70,000 gallons of aviation fuel on fire.
The US suffered three soldiers killed in action and they counted a total of 69 Japanese bodies in the overall action.
The damage and devastation was caused by only ten commandos from the belly-landed aircraft with a few stragglers from the crashed aircraft joining in. Imagine what might have occurred if all 136 commandos landed intact!
The aftermath
The next day not knowing if the Geritsu attacks were successful in destroying the fighters on the base, the Japanese launched phase two of their plan with massive kamikaze attacks against American shipping and US Navy
The kamikazes were largely defeated as the airbase at Yontan was not silenced and fighter from there and Kadena were able to intercept the incoming Japanese kamikaze aircraft.
Interestingly, the raid was deemed a success in Japan and served as a template for future planned operations. A much larger version of the raid was planned for the Marianas with the B-29 bases being the primary target. The larger raid planned for the 19–23rd of August envisioned 60 transports and up to 900 commandos. Japan surrended on August 15th and the operation was canceled.
To this day, the story of the Geritsu Kuteitai is revered in Japan and their bravery celebrated every May 24th. There are two memorials to the Geritsu unit in Okinawa.
