Editing Fu-Go balloon bomb

{{Short description|WWII Japanese incendiary weapon}}
{{Good article}}
{{Use mdy dates|date=April 2016}}
{{Infobox aircraft
| name    = Fu-Go<br/>ふ号
| image   = Japanese fire balloon Moffett.jpg
| size    = 220px
| alt     = 
| image_caption = Fu-Go balloon reinflated in California, January 1945
| aircraft_type            = [[Incendiary balloon]]
| national_origin = Japan
| manufacturer    = [[Imperial Japanese Army]] (A-Type)<br>[[Imperial Japanese Navy]] (B-Type)
| first_flight    =
| introduction      = November 3, 1944
| retired         = April 20, 1945
| primary_user    = Imperial Japanese Army
| more_users      =
| produced        = 1944–1945
| number_built    = About 9,300
| developed_into  = 
}}

{{Nihongo|'''Fu-Go'''|ふ号[兵器]|fugō [heiki]|{{lit}} "Code 'Fu' [Weapon]"}} was an {{nihongo|[[incendiary balloon]] weapon|風船爆弾|fūsen bakudan|{{lit}} "balloon bomb"}} deployed by Japan against the United States during [[World War II]]. It consisted of a [[hydrogen]]-filled paper balloon {{convert|33|ft|m}} in diameter, with a payload of four {{convert|11|lb|kg|adj=on}} [[Incendiary device|incendiary devices]] and one {{convert|33|lb|kg|adj=on}} high-explosive [[Anti-personnel weapon|anti-personnel bomb]]. The uncontrolled balloons were carried over the Pacific Ocean from Japan to North America by fast, high-altitude air currents, today known as the [[jet stream]], and used a sophisticated sandbag [[ballast]] system to maintain their altitude. The bombs were intended to ignite large-scale forest fires and spread panic.

Between November 1944 and April 1945, the [[Imperial Japanese Army]] launched about 9,300 balloons from sites on coastal [[Honshu]], of which about 300 were found or observed in the U.S., Canada, and Mexico. The bombs were ineffective as fire starters due to damp seasonal conditions, with no forest fires being attributed to the offensive. A U.S. media censorship campaign prevented the Imperial Army from learning of the offensive's results. On May 5, 1945, six civilians were killed by one of the bombs near [[Bly, Oregon]], becoming the war's only fatalities in the contiguous U.S. The Fu-Go balloon bomb was the first weapon system with intercontinental range, predating the [[intercontinental ballistic missile]].

== Background ==
The balloon bomb concept was developed by the [[Imperial Japanese Army]]'s [[Noborito Research Institute|Ninth Technical Research Institute]] (also known as the Noborito Research Institute), tasked with creating special weapons.{{sfn|Coen|2014|p=16}} In 1933, Lieutenant General Reikichi Tada started a balloon bomb program at Noborito designated Fu-Go,{{efn|Every Noborito project was assigned a [[code name]] ending with {{nihongo|''-go''|号}}, a numbering suffix. The balloon bomb project's name was derived from {{nihongo|''fūsen''|風船}}, the Japanese word for "balloon".{{sfn|Coen|2014|pp=18–19}}}} which proposed a [[hydrogen]]-filled balloon {{convert|13|ft|m}} in diameter with a time fuse, capable of delivering bombs up to {{convert|70|mi|km}}. The project was not completed and stopped by 1935.{{sfn|Mikesh|1973|p=3}}

After the [[Doolittle Raid]] in April 1942, in which American planes bombed the Japanese mainland, the [[Imperial General Headquarters]] directed Noborito to develop a retaliatory bombing capability against the U.S.{{sfn|Coen|2014|pp=15–16}} In mid-1942, Noborito investigated several proposals, including long-range bombers that could make one-way sorties from Japan to cities on the U.S. West Coast, and small bomb-laden [[seaplane]]s which could be launched from submarines.{{sfn|Coen|2014|pp=16–17}} On September 9, 1942, the latter was tested in the [[Lookout Air Raid]], in which a [[Yokosuka E14Y]] seaplane was launched from a submarine off the Oregon coast. Warrant Officer [[Nobuo Fujita]] dropped two large [[Incendiary device|incendiary bomb]]s in [[Siskiyou National Forest]] in the hopes of starting a forest fire and safely returned to the submarine. Response crews spotted the plane and contained the small blazes. The program was cancelled by the [[Imperial Japanese Navy|Imperial Navy]].{{sfn|Coen|2014|p=17}}

Also in September 1942, Major General Sueki Kusaba, who had served under Tada in the original balloon bomb program in the 1930s, was assigned to the laboratory and revived the Fu-Go project with a focus on longer flights.{{sfn|Coen|2014|p=17}} The Oregon air raid, while not achieving its strategic objective, had demonstrated the potential of using unmanned balloons at a low cost to ignite large-scale forest fires.{{sfn|Coen|2014|p=25}} According to U.S. interviews with Japanese officials after the war, the balloon bomb campaign was undertaken "almost exclusively for home propaganda purposes", and the Army had little expectation of its effectiveness.{{sfn|Coen|2014|p=192}}

== Design and development ==
By March 1943, Kusaba's team developed a {{convert|20|ft|m|adj=on}} design capable of floating at {{convert|25,000|ft|m}} for up to 30 hours.{{sfn|Mikesh|1973|p=6}} The balloons were constructed from four to five thin layers of ''[[washi]]'', a durable paper derived from the [[paper mulberry]] (''kōzo'') bush, which were glued together with ''[[konjac|konnyaku]]'' (Japanese potato) paste. The Army mobilized thousands of teenage girls at high schools across the country to laminate and glue the sheets together, with final assembly and inflation tests at large indoor arenas including the Nichigeki Music Hall and [[Ryōgoku Kokugikan]] sumo hall in Tokyo.{{sfn|Coen|2014|pp=26–27}} The original proposal called for night launches from submarines located {{convert|600|mi|km}} off of the U.S. coast, a distance the balloons could cover in 10 hours. A calibrated timer would release a {{convert|11|lb|kg|adj=on}} incendiary bomb at the end of the flight.{{sfn|Coen|2014|p=19}} Two submarines ([[Japanese submarine I-34|''I-34'']] and [[Japanese submarine I-35|''I-35'']]) were prepared and two hundred balloons were produced by August 1943, but attack missions were postponed due to the need for submarines as weapons and food transports.{{sfn|Mikesh|1973|p=6}}

Engineers next investigated the feasibility of balloon launches against the United States from the Japanese mainland, a distance of at least {{convert|6,000|mi|km}}.{{sfn|Coen|2014|pp=26–27}} Engineers sought to make use of strong seasonal air currents discovered flowing from west to east at high altitude and speed over Japan, today known as the [[jet stream]]. The currents had been investigated by Japanese scientist [[Wasaburo Oishi]] in the 1920s. In late 1943, the Army consulted Hidetoshi Arakawa of the [[Japan Meteorological Agency|Central Meteorological Observatory]], who used Oishi's data to extrapolate the air currents across the Pacific Ocean and estimate that a balloon released in winter and that maintained an altitude of {{convert|30,000|to|35,000|ft|m}} could reach the North American continent in 30 to 100 hours. Arakawa further found that the strongest winds blew from November to March at speeds approaching {{convert|200|mph|kph}}.{{sfn|Coen|2014|pp=20–22}}

<gallery mode="packed">
File:342-FH-3B23426 (18160066205).jpg|Fu-Go carriage, with labeled ring, electrical circuits, fuses, ballast, and bombs
File:342-FH-3B23434 (18160038915).jpg|Top view of carriage assembly, with control device removed
File:342-FH-3B23427 (17537483644).jpg|Altitude control device, with central master [[aneroid barometer]] and backups
File:342-FH-3B23433 (17537463564).jpg|Bottom view of carriage fuses
File:342-FH-3B23428 (18160060525).jpg|Recovered Fu-Go at the moment a blowout plug is detonated
</gallery>

Changing pressure levels in a fixed-volume balloon posed technical challenges. During the day, heat from the sun increased pressure, risking the balloon rising above the air currents or bursting. A relief valve was added to allow gas to escape when the envelope's internal pressure rose above a set level. At night, cool temperatures risked the balloon falling below the currents, an issue that worsened as gas was released. To resolve this, engineers developed a sophisticated [[ballast]] system with 32 sandbags mounted around a cast aluminum wheel, with each sandbag connected to [[gunpowder]] blowout plugs. The plugs were connected to three redundant [[aneroid barometer]]s calibrated for an altitude between {{convert|25,000|and|27,000|ft|m}}, below which one sandbag was released; the next plug was armed two minutes after the previous plug was blown. A separate altimeter set between {{convert|13,000|and|20,000|ft|m}} controlled the later release of the bombs. A one-hour activating fuse for the altimeters was ignited at launch, allowing the balloon time to ascend above these two thresholds. Tests of the design in August 1944 indicated success, with several balloons releasing [[radiosonde]] signals for up to 80 hours (the maximum time allowed by the batteries). A self-destruct system was added; a three-minute fuse triggered by the release of the last bomb would detonate a block of [[picric acid]] and destroy the carriage, followed by an 82-minute fuse that would ignite the hydrogen and destroy the envelope.{{sfn|Coen|2014|pp=33–40}}

[[File:342-FH-3B23429c (17972344110).jpg|thumb|right|B-Type rubberized silk balloon, with outline of a human for scale]]

In late 1942, the Imperial General Headquarters had directed the Navy to begin its own balloon bomb program in parallel with the Army project. Lieutenant Commander Kiyoshi Tanaka headed a group which developed a {{convert|30|ft|m|adj=on}} rubberized silk balloon, designated the B-Type (in contrast to the Army's A-Type). The silk material was an effort to create a flexible envelope that could withstand pressure changes. The design was tested in August 1944, but the balloons burst immediately after reaching altitude, determined to be the result of faulty rubberized seams. The Navy program was subsequently consolidated under Army control, due in part to the declining availability of rubber as the war continued.{{sfn|Coen|2014|pp=32–33}} The B-Type balloons were later equipped with a version of the A-Type's ballast system and tested on November 2, 1944; one of these balloons, which was not loaded with bombs, became the first to be recovered by Americans after being spotted in the water off [[San Pedro, Los Angeles|San Pedro, California]], on November 4.{{sfn|Coen|2014|p=42}}

The final A-Type design was {{convert|33|ft|m}} in diameter, and had a gas volume of {{convert|19,000|cuft|m3}} and a lifting capacity of {{convert|300|lb|kg}} at operating altitude.{{sfn|Coen|2014|p=33}} The bomb payload most commonly carried was:

* four {{convert|11|lb|kg|adj=on}} [[thermite]] [[incendiary device]]s, consisting of a steel tube {{convert|16|in|cm}} long and {{convert|4|in|cm}} in diameter with a mechanical impact fuse;
* one Type 92 {{convert|33|lb|kg|adj=on}} high-explosive [[Anti-personnel weapon|anti-personnel bomb]], containing a block of [[picric acid]] or [[TNT]] surrounded by shrapnel rings;
* or alternatively to the anti-personnel bomb, one Type 97 {{convert|26|lb|kg|adj=on}} incendiary bomb, containing three [[magnesium]] containers of thermite.{{sfn|Mikesh|1973|pp=21, 58-61}}

== Offensive and defenses==
[[File:Fu-Go balloon bomb launch sites and following stations.jpg|thumb|Fu-Go launching sites and flight-following stations on [[Honshu]]]]

A balloon launch organization of three battalions was formed. The first battalion included headquarters and three squadrons, totaling 1,500 men, at nine launch stations at [[Kitaibaraki, Ibaraki|Otsu]] in [[Ibaraki Prefecture]]. The second battalion of 700 men in three squadrons operated six launch stations at [[Ichinomiya, Chiba]], and the third battalion of 600 men in two squadrons operated six launch stations at [[Iwaki, Fukushima|Nakoso, Fukushima]]. The Otsu site featured its own hydrogen plant, while the second and third battalions used hydrogen gas transported from factories around Tokyo. The combined launching capacity of the sites was about 200 balloons per day, with 15,000 launches planned through March.{{sfn|Mikesh|1973|pp=16–17, 22–23}} The Army estimated that only 10 percent of the balloons would survive the journey across the Pacific Ocean.{{sfn|Coen|2014|p=25}}

Each launch pad consisted of anchor screws drilled into the ground in a circle the same diameter as the balloons. After anchoring an envelope, hoses were used to fill it with {{convert|8,100|cuft|m3}} of hydrogen while it was tied down with guide ropes and detached from the anchors. The carriage was attached with shroud lines, and the guide ropes were untied. Each launch required a crew of 30 men and took between 30 minutes and one hour, depending on the presence of surface winds.{{sfn|Mikesh|1973|p=|pp=22–23, 63}} The best time for launches was after a [[High-pressure area|high-pressure front]] had passed, and wind conditions were best before the onshore breezes at sunrise. Suitable wind conditions were only expected for three to five days a week, for a total of about fifty days during the winter period of maximum jet stream velocity.{{sfn|Mikesh|1973|pp=22–23}}

The first balloons were launched on November 3, 1944. Some balloons in each of the launches carried radiosonde equipment instead of bombs, and were tracked by [[direction finding]] stations to follow their progress.{{sfn|Mikesh|1973|pp=21,24}} Two weeks after the discovery of the B-Type balloon off San Pedro, an A-Type balloon was found in the ocean off [[Kailua, Hawaii]], on November 14.{{efn|A second B-Type balloon was found near [[Yerington, Nevada]], on November 9, 1944, but was not reported until June 1945.{{sfn|Coen|2014|p=222}}}} More were found near [[Thermopolis, Wyoming]], on December 6 (with an explosion heard by witnesses, and a crater later located) and near [[Kalispell, Montana]], on December 11, followed by finds near [[Marshall, Alaska|Marshall]] and [[Holy Cross, Alaska]], and [[Estacada, Oregon]], later in the month.{{sfn|Mikesh|1973|p=28}} Authorities were placed on heightened alert, and forest rangers were ordered to report landings and recoveries. The balloons continued to be discovered across North America, with sightings and partial or full recoveries in [[Territory of Alaska|Alaska]], [[Arizona]], [[California]], [[Colorado]], [[Territory of Hawaii|Hawaii]], [[Idaho]], [[Iowa]], [[Kansas]], [[Michigan]] (where an incendiary bomb was found at [[Farmington, Michigan|Farmington]] in the easternmost incident), [[Montana]], [[Nebraska]], [[Nevada]], [[North Dakota]], [[Oregon]], [[South Dakota]], [[Texas]], [[Utah]], [[Washington (state)|Washington]], and [[Wyoming]]; in Canada in [[Alberta]], [[British Columbia]], [[Manitoba]], [[Saskatchewan]], and the [[Northwest Territories|Northwest]] and [[Yukon Territories]]; in Mexico in [[Territory of Baja California Norte|Baja California Norte]] and [[Sonora]]; and at sea.{{efn|On March 13, 1945, two balloons returned to Japan, landing near [[Hakodate, Hokkaido]], and in [[Akita Prefecture]]. Both fell in snow and caused no damage.{{sfn|Mikesh|1973|p=16}}}}{{sfn|Mikesh|1973|pp=69–77}} By August 1945, the U.S. Army had recorded 285 balloon incidents (28 by January, 54 in February, 114 in March, 42 in April, 16 in May, 17 in June, and 14 in July).{{sfn|Mikesh|1973|p=77}}

<gallery mode="packed">
File:342-FH-3B23422 (18161219731).jpg|Balloon found near [[Alturas, California]], on January 10, 1945, reinflated at [[Moffett Field]]
File:342-FH-3B23424 (18156536642).jpg|Balloon found near [[Bigelow, Kansas]], on February 23, 1945
File:342-FH-3B23423 (17973857089).jpg|Balloon found near [[Nixon, Nevada]], on March 29, 1945
FIle:342-FH-3B23432 (18160047105).jpg|Aerial photograph of a balloon taken from an American plane
File:342-FH-3B23437 (18133550866).jpg|Another aerial photograph of a balloon
</gallery>

Most U.S. defense plans were only fully implemented after the offensive ended in April 1945. In response to the threat of wildfires in the [[Pacific Northwest]] during the summer months, the Army's [[Western Defense Command]] (WDC), [[Fourth Air Force]], and [[Army Service Forces#Service Commands|Ninth Service Command]] organized the "Firefly Project" with [[Stinson L-5 Sentinel]] and [[Douglas C-47 Skytrain]] aircraft and 2,700 troops, including 200 paratroopers from the all-black [[555th Parachute Infantry Battalion (United States)|555th Parachute Infantry Battalion]], who were deployed in 36 firefighting missions between May and October 1945.{{sfn|Mikesh|1973|p=29}}<ref name=":0">{{Cite web |last=Bradsher |first=Greg |last2=Naylor |first2=Sylvia |date=2015-02-12 |title=Firefly Project and the 555th Parachute Infantry Battalion ("Smoke Jumpers") |url=https://text-message.blogs.archives.gov/2015/02/12/firefly-project-and-the-555th-parachute-infantry-battalion-smoke-jumpers/ |access-date=2023-03-28 |website= |publisher=National Archives and Records Administration |language= |archive-date=March 28, 2023 |archive-url=https://web.archive.org/web/20230328022321/https://text-message.blogs.archives.gov/2015/02/12/firefly-project-and-the-555th-parachute-infantry-battalion-smoke-jumpers/ |url-status=live }}</ref> The Army used the [[United States Forest Service|U.S. Forest Service]] as a proxy agency, unifying fire suppression communications between federal and state agencies and modernizing the service through an influx of military personnel, equipment, and tactics.<ref name=Karns>{{Cite journal |last=Karns |first=Jameson |date=March 2017 |title=A Fire Management Assessment of Fugo |url=https://www.frames.gov/catalog/25973 |journal=Fire Management Today |volume=57 |pages=53–57 |access-date=August 1, 2022 |archive-date=February 10, 2023 |archive-url=https://web.archive.org/web/20230210201947/https://www.frames.gov/catalog/25973 |url-status=live }}</ref> In the WDC's "Lightning Project", health and agricultural officers, veterinarians, and [[4-H]] clubs were instructed to report any new diseases of crops or livestock caused by potential [[biological warfare]]. Stocks of decontamination chemicals, ultimately unused, were shipped to key points in the western states.{{sfn|Mikesh|1973|p=29}} Although biological warfare had been a concern for months, the WDC's plan was not formalized and fully implemented until July 1945. A sub-section of the project, "Arrow", provided for rapid air transportation of all balloon remains to the Technical Air Intelligence Center laboratory in [[Washington, D.C.]], for biological analysis.{{sfn|Coen|2014|pp=137–139}} A U.S. investigation after the war concluded there had not been plans for chemical or biological payloads.{{sfn|Coen|2014|pp=191–193}}[[File:Japanese fire balloon shotdown gun.jpg|thumb|Balloon shot down by [[Lockheed P-38 Lightning|P-38 Lightning]] fighters at [[Attu Island|Attu]], [[Aleutian Islands]], Alaska, on April 13, 1945]]

[[Army Air Forces]] and Navy fighter planes were scrambled on several occasions to intercept balloons, but they had little success due to inaccurate sighting reports, bad weather, and the very high altitude at which they traveled.{{sfn|Mikesh|1973|p=29}} In all, only about 20 balloons were shot down by U.S. and Canadian pilots.{{efn|This figure includes 11 balloons shot down by the [[U.S. Air Force]] over the [[Aleutian Islands]] in Alaska: over [[Shemya]] on January 25, 1945; [[Attu Island|Attu]] on April 12; and nine more over Attu on April 13. Four balloons were shot down over the continental U.S.: over [[North Bend, Oregon]], on February 22; [[Calistoga, California]], on February 23; [[Reno, Nevada]], on March 22; and [[Imperial Valley, California]], on March 28. The [[Royal Canadian Air Force]] shot down balloons over [[Sumas, Washington]], on February 21 and [[Galiano Island]] in British Columbia on March 10.{{sfn|Coen|2014|pp=222–245}}}}{{sfn|Coen|2014|pp=222–245}} Attempts to track the radiosonde balloons produced 95 suspected signals, but they were of little use due to the very low proportion of balloons with transmitters, and observed fading of signals as they approached. Experiments on recovered balloons in February 1945 to determine their radar reflectivity were unsuccessful.{{sfn|Mikesh|1973|pp=32–34}} In the "Sunset Project", initiated in early April and fully operational by June, the Fourth Air Force attempted to detect balloons with search radars at [[ground-controlled interception]] sites in coastal Washington, but the project detected nothing and was cancelled in early August.{{sfn|Mikesh|1973|pp=34–36}} 

Few American officials believed at first that the balloons could have come directly from Japan. Early U.S. theories speculated that they were launched from [[German prisoners of war in the United States|German prisoner of war camps]] or from [[Japanese American internment|Japanese-American internment centers]]. After bombs of Japanese origin were found, it was believed that the balloons were launched from coastal submarines.{{sfn|Mikesh|1973|p=28}} Statistical analysis of valve serial numbers suggested that tens of thousands of balloons had been produced.{{sfn|Coen|2014|p=192}} The mineral and [[diatom]] composition of sand from the sandbags was studied by the [[Military Geology Unit]] of the [[United States Geological Survey]], which assessed its origin as [[Shiogama|Shiogama, Miyagi]], or less likely, Ichinomiya, Chiba, only the latter being correct. [[Aerial reconnaissance]] of Shiogama in May 1945 showed what was mistakenly interpreted as inflated balloons and a possible launch area at the beach.{{sfn|Mikesh|1973|pp=34–36}}

===Censorship campaign===
On January 4, 1945, the U.S. [[Office of Censorship]] sent a confidential memo to newspaper editors and radio broadcasters asking that they give no publicity to balloon incidents; this proved highly effective, with the agency sending another memo three months later stating that cooperation had been "excellent" and that "there is no question that your refusal to publish or broadcast information about these balloons has baffled the Japanese, annoyed and hindered them, and has been an important contribution to security."{{sfn|Coen|2014|pp=162, 169}} The Imperial Army only ever learned of the balloon at Kalispell from an article in the Chinese newspaper ''[[Ta Kung Pao]]'' on December 18, 1944.{{sfn|Coen|2014|p=83}} The Kalispell find was originally reported on December 14 by the ''Western News'', a weekly published in [[Libby, Montana]]; the story later appeared in articles in the January 1, 1945, editions of ''[[Time (magazine)|Time]]'' and ''[[Newsweek]]'' magazines, as well as on the front page of the January 2 edition of ''[[The Oregonian]]'' of [[Portland, Oregon]], before the Office of Censorship sent the memo.{{sfn|Coen|2014|p=68}} Starting in mid-February 1945, Japanese propaganda broadcasts falsely announced numerous fires and a panicked American public, further claiming casualties in the hundreds or thousands.{{sfn|Mikesh|1973|p=37}}

One breach occurred in late February, when Representative [[Arthur L. Miller]] mentioned the balloons in a weekly column he sent to all 91 newspapers in his Nebraska district, which stated in part: "As a final act of desperation, it is believed that the Japs may release fire balloons aimed at our great forests in the northwest". In response, intelligence officers at the [[Seventh Service Command]] in Omaha contacted the editors at all 91 papers, requesting censorship; this was largely successful, with only two papers printing the column.{{sfn|Coen|2014|p=162}} In late March, the [[United Press International|United Press]] (UP) wrote a detailed article on the balloons intended for its national distributors; the Army officer who reported the breach commented that it included "a lot of mechanical detail on the thing, in addition to being a hell of a scare story".{{sfn|Coen|2014|p=167}} Censors contacted the UP, which replied that the article had not yet been [[Teletype|teletyped]]; all five copies were retrieved and destroyed. Investigators determined the information originated from a briefing to Colorado state legislators, which had been leaked in an open session.{{sfn|Coen|2014|p=168}} 

In late April, censors investigated the nationally-syndicated comic strip ''[[Tim Tyler's Luck]]'' by [[Lyman Young]], which depicted a Japanese balloon recovered by the crew of an U.S. submarine. In subsequent weeks, its protagonists fought monster vines which sprang from seeds the balloon was carrying, created by an evil Japanese horticulturalist. A few weeks later, the comic strip ''[[The Adventures of Smilin' Jack|Smilin' Jack]]'' by [[Zack Mosley]] depicted a plane crashing into a Japanese balloon, which exploded and started a fire upon falling to the ground.{{sfn|Coen|2014|pp=164–167}} In both cases, the Office of Censorship deemed it unnecessary to censor the [[Sunday comics]].{{sfn|Coen|2014|p=167}}

== Abandonment and results ==
{{multiple image
| align             = center
| total_width       = 440px
| perrow            = 2
| image_style       = border:none;
| image1            = Fu-Go balloon bomb incident locations, Alaska.jpg
| image2            = Fu-Go balloon bomb incident locations, Canada.jpg
| image3            = Fu-Go balloon bomb incident locations, Hawaii.jpg
| image4            = Fu-Go balloon bomb incident locations, United States and Mexico.jpg
| footer            = Map of Fu-Go incident locations in North America, marked with black dots
}}

By mid-April 1945, Japan lacked the resources to continue manufacturing balloons, with both paper and hydrogen in short supply. Furthermore, the Army had little evidence that the balloons were reaching North America, let alone causing damage. The campaign was halted, with no intention to revive it when the jet stream regained strength in fall 1945.{{sfn|Coen|2014|p=193}} The last balloon was launched on April 20.<ref name=":0" /> In total, about 9,300 were launched in the campaign (about 700 in November 1944, 1,200 in December, 2,000 in January 1945, 2,500 in February, 2,500 in March, and 400 in April), of which about 300 were found or observed in North America.{{sfn|Mikesh|1973|p=17}} The Fu-Go balloon bomb is considered to be the first weapon system in history with intercontinental range,<ref>{{cite web |last1=Rizzo |first1=Johnna |date=27 May 2013 |title=Japan's Secret WWII Weapon: Balloon Bombs |url=https://www.nationalgeographic.com/science/article/130527-map-video-balloon-bomb-wwii-japanese-air-current-jet-stream |access-date=28 November 2022 |website=National Geographic |language=en |archive-date=November 16, 2022 |archive-url=https://web.archive.org/web/20221116110407/https://www.nationalgeographic.com/science/article/130527-map-video-balloon-bomb-wwii-japanese-air-current-jet-stream |url-status=dead }}</ref> a significant development in warfare which was followed by the advent of the world's first [[intercontinental ballistic missile]] (ICBM), the [[Soviet Union]]'s [[R-7 Semyorka|R-7]], in 1957.{{sfn|Coen|2014|p=6}}{{sfn|Mikesh|1973|p=1}}

Only "one or two" small grass fires were attributed to the balloon bombs.<ref name=":0" /> As predicted by Imperial Army officials, the winter and spring launch dates had limited the chances of the incendiaries starting fires due to the high levels of precipitation in the Pacific Northwest; forests were generally snow-covered or too damp to catch fire easily.{{sfn|Mikesh|1973|pp=7,25}} Furthermore, much of the western U.S. received disproportionately more precipitation in 1945 than in any other year in the decade, with some areas receiving {{convert|4|to|10|inches|cm}} of precipitation more than other years.<ref name=Karns /> The most damaging attack occurred on March 10, 1945, when a balloon descended near [[Toppenish, Washington]], and collided with [[Electric power transmission|electric transmission lines]], causing a [[short circuit]] which cut off power to the [[Manhattan Project]]'s production facility at the state's [[Hanford Engineer Works]]. Backup devices restored power to the site, but it took three days for its [[plutonium]]-producing [[nuclear reactor]]s to be restored to full capacity; the plutonium was later used in [[Fat Man]], the atomic bomb [[Atomic bombings of Hiroshima and Nagasaki|dropped on Nagasaki]].{{sfn|Coen|2014|pp=139–140}}

== Single lethal attack ==
[[File:Mitchell Monument, Bly, Oregon (6149865447).jpg|thumb|right|[[Mitchell Monument]] in 2011]]

On May 5, 1945, six civilians were killed near [[Bly, Oregon]], when they discovered one of the balloon bombs in [[Fremont National Forest]], becoming the only fatalities from Axis action in the continental U.S. during the war.<ref>{{cite book |last=Brendan |first=Coyle| author-link = Brendan Coyle |year=2013 |title=Enemy offshore! |publisher=Heritage House Publishing Company Ltd |location=Vancouver |page=128 |isbn=978-1-927527-53-5}}</ref><ref name=NRHP/> Reverend [[Archie E. Mitchell|Archie Mitchell]] and his pregnant wife Elsie (age 26) drove up [[Gearhart Mountain Wilderness|Gearhart Mountain]] that day with five of their [[Sunday school]] students for a picnic.<ref>{{cite web |title=Cherry-Red Shrapnel |url=https://www.check-six.com/Crash_Sites/Bly_Incident_FuGo-1945.htm |website=Check-Six.com |access-date=3 September 2024}}</ref> While Archie was parking the car, Elsie and the children discovered a balloon and carriage, loaded with an anti-personnel bomb, on the ground. A large explosion occurred; the four boys (Edward Engen, 13; Jay Gifford, 13; Dick Patzke, 14; and Sherman Shoemaker, 11) were killed instantly, while Elsie and Joan Patzke (13) died from their wounds shortly afterwards.{{sfn|Coen|2014|pp=1–4}} An Army investigation concluded that the bomb had likely been kicked or dropped, and that it had lain undisturbed for about one month before the incident.<ref name=":0" /> The U.S. press blackout was lifted on May 22 so the public could be warned of the balloon threat.{{sfn|Coen|2014|pp=177–179}}

A memorial, the [[Mitchell Monument]], was built in 1950 at the site of the explosion,{{sfn|Coen|2014|p=205}} and the surrounding Mitchell Recreation Area was listed on the [[National Register of Historic Places]] in 2003.<ref name=NRHP>{{cite web |url=https://npgallery.nps.gov/AssetDetail/NRIS/03000050 |title=Mitchell Recreation Area |date=February 20, 2003 |website=National Register of Historic Places |publisher=National Park Service, U.S. Department of the Interior |access-date=February 8, 2023 |archive-date=February 8, 2023 |archive-url=https://web.archive.org/web/20230208002848/https://npgallery.nps.gov/AssetDetail/NRIS/03000050 |url-status=live }}</ref> A [[ponderosa pine]] near the site bears scars on its trunk from the bomb's shrapnel. In 1987, a group of Japanese women involved in Fu-Go production as schoolgirls delivered [[One thousand origami cranes|1,000 paper cranes]] to the victims' families as a symbol of peace and healing, and six cherry trees were planted at the site on the incident's 50th anniversary in 1995.{{sfn|Coen|2014|p=211}}

==After World War II==
[[File:Fu-Go balloon bomb - edo-tokyo musuem - 2021 12 3.webm|thumb|thumbtime=1|Small-scale model (1:5 balloon, 1:2 carriage) of a Fu-Go balloon at [[Edo-Tokyo Museum]]]]

All Japanese records on the Fu-Go program were destroyed in compliance with a directive issued on August 15, 1945, the day [[Surrender of Japan|Japan announced its surrender]]. Thus, a single interview with Lieutenant Colonel Terato Kunitake of the [[Imperial Japanese Army General Staff Office|Army General Staff]] and a Major Inouye became the source of nearly all information on the project's objectives for U.S. investigators. A five-volume report, prepared by a team led by [[Karl Taylor Compton|Karl T. Compton]] of the [[Office of Scientific Research and Development]] and [[Edward Moreland|Edward L. Moreland]] of [[Massachusetts Institute of Technology|MIT]], was later submitted to President [[Harry S. Truman]].{{sfn|Coen|2014|pp=191–192}}

The remains of balloons have continued to be discovered after the war. At least eight were found in the 1940s, three in the 1950s, two in the 1960s, and one in the 1970s.<ref>{{cite book |last=Peebles |first=Curtis| author-link = Curtis Peebles |year=1991 |title=The Moby Dick Project: Reconnaissance Balloons Over Russia |publisher=Smithsonian Institution Press |location=Washington |page=82 |isbn=978-1-56098-025-4}}</ref> A carriage with a live bomb was found near [[Lumby, British Columbia]], in 2014 and detonated by a [[Royal Canadian Navy]] ordnance disposal team.<ref>{{cite news |title=Military unit blows WWII-era Japanese balloon bomb to 'smithereens' |url=https://www.theglobeandmail.com/news/british-columbia/object-found-in-forest-may-be-second-world-war-era-japanese-balloon-bomb/article21065545/ |access-date=August 10, 2022 |work=The Globe and Mail |agency=The Canadian Press |date=October 10, 2014 |archive-date=August 10, 2022 |archive-url=https://web.archive.org/web/20220810224923/https://www.theglobeandmail.com/news/british-columbia/object-found-in-forest-may-be-second-world-war-era-japanese-balloon-bomb/article21065545/ |url-status=live }}</ref> Remains of another balloon were found near [[McBride, British Columbia]], in 2019.<ref>{{cite news |title=Looking for goats, man finds WWII bomb |first=Andru |last=McCracken |date=October 22, 2019 |newspaper=The Rocky Mountain Goat |url=https://www.therockymountaingoat.com/2019/10/looking-for-goats-man-finds-wwii-bomb/ |access-date=January 29, 2020 |archive-date=January 29, 2020 |archive-url=https://web.archive.org/web/20200129195258/https://www.therockymountaingoat.com/2019/10/looking-for-goats-man-finds-wwii-bomb/ |url-status=live }}</ref> Many war museums in the U.S. and Canada hold Fu-Go fragments, including the [[National Air and Space Museum]] and the [[Canadian War Museum]].{{sfn|Coen|2014|pp=64, 75, 231}}

==See also==
* [[E77 balloon bomb]] – 1950s U.S. biological weapon inspired by Fu-Go
* [[History of military ballooning]] – Includes Austrian use of balloon bombs at Venice in 1849
* [[Operation Outward]] – WWII British attack on Germany with balloon bombs
* [[WS-124A Flying Cloud]] – 1950s U.S. Air Force balloon bomb program

==Notes==
{{Notelist}}

==References==
{{Reflist}}

===Works cited===
* {{cite book |last=Coen |first=Ross |title=Fu-Go: The Curious History of Japan's Balloon Bomb Attack on America |url=https://archive.org/details/fugocurioushisto0000coen |date=2014 |publisher=University of Nebraska Press |location=Lincoln, NE |isbn=978-0-80325-667-5 }}
* {{cite book |last=Mikesh |first=Robert C. |title=Japan's World War II Balloon Bomb Attacks on North America |url=https://repository.si.edu/handle/10088/18679 |date=1973 |publisher=Smithsonian Institution Press |location=Washington, D.C. |hdl=10088/18679 |isbn=978-0-87474-911-3 }}

==Further reading==
* {{cite journal |last=Conley |first=Cornelius W. |title=The Great Japanese Balloon Offensive |journal=Air University Review |volume=February–March 1968 |pages=68–83 |ref=none }}
* {{cite magazine |last=McPhee |first=John |title=Balloons of War |magazine=The New Yorker |date=29 January 1996 |pages=52–60 |ref=none }}
* {{cite book |last=Webber |first=Bert |title=Retaliation: Japanese Attacks and Allied Countermeasures on the Pacific Coast in World War II |url=https://archive.org/details/retaliationjapan0000webb |date=1975 |publisher=Oregon State University Press |location=Corvallis |isbn=978-0-87071-076-6|ref=none}}

==External links==
{{Commons category|Fu-Go fire balloons (World War II)}}
* [http://www.allworldwars.com/Japanese-Balloon-and-Attached-Devices.html Report on Fu-Go balloons by the U.S. Technical Air Intelligence Center, May 1945]
* {{Internet Archive short film|gov.archives.arc.13084|Japanese Paper Balloon}}

{{Authority control}}

[[Category:American Theater of World War II]]
[[Category:Balloon weaponry]]
[[Category:Balloons (aeronautics)]]
[[Category:Incendiary weapons]]
[[Category:Japanese inventions]]
[[Category:Weapons and ammunition introduced in 1944]]
[[Category:World War II weapons of Japan]]