The story begins with the Japanese bombing of Pearl Harbor in December 1941. That event may have started the war but, in the normal but tragic cycle of war, it led to aggressively planned and executed Allied attacks on the Japanese archipelago five months later. In particular, the Doolittle raid on Tokyo in April 1942 left the Japanese determined to retaliate in turn, if at all possible, on the American mainland. But how could that be accomplished? Robert C. Mikesh's detailed analysis of the balloon bomb story1 tells us that early in the 1940s, Japanese researchers had discovered high-altitude "rivers of air" (later known as jet streams). They had also used experimental, radio-equipped balloons to demonstrate that a transpacific balloon flight would require only 30 to 100 hours of travel time. Given 6,200 total miles, computations showed the balloons were capable of speeds between 60 and 200 miles per hour. The Japanese military realized that if they could develop the right balloon, hardware, and bombs, they would be looking at the world's first intercontinental weapons delivery system requiring no propellant whatsoever! Researchers and military leaders were so excited about the prospects of generating fear, death, and confusion in the American homeland, that between 1942 and 1945 they invested 9 million yen (equivalent to 2 million prewar dollars) in developing, building, and successfully launching 9,000 of these balloons toward North America. Two key problems faced the Japanese military in their effort to make their early trial balloons fully operational weapons of war. First, designers determined that the entire payload would come to about 320 pounds. A 33-foot-diameter balloon could lift that weight but only if the balloon itself was kept to no more than an additional 130 to 175 pounds. Also, for the project to succeed, they would Washi at War: Japan's WWII Balloon Bombs timothy barrett Recovered balloon bomb ring and apparatus on display at the Canadian War Museum in Ottawa, Canada. Entire assembly was suspended from a 33-foot-diameter paper balloon by 19 shroud lines each 49 feet long. Key components are as follows: clear double-walled celluloid battery box on top held non-freeze liquid between the walls to help control minimum temperatures; inner box held 2.3 volt lead-acid storage battery. Clear celluloid was used to take advantage of solar radiation to help sustain battery life. Battery box sat atop the main control box wrapped with time delay fuses. Wooden control box contains four barometric contractors or aneroids that were wired to 72 explosive pins on the lower ring. The purpose of three of the aneroids (one master and two backup) was to control the lower altitude of the balloon by releasing ballast or bombs. The forth aneroid controlled explosive charges that destroyed the balloon and apparatus. Sandbags were made of handmade paper and weighed about seven pounds each. Specific ordinance varied but this balloon carried four 11- pound incendiary bombs and one 33-pound antipersonnel bomb. Courtesy of Canadian War Museum, Ottawa. - hand papermaking have to develop a lightweight, gas-tight balloon made from materials not otherwise crucial to the war effort. Early experiments used rubberized silk cloth, but the balloons were too heavy and the materials too costly and essential for other needs. In the 1930s and early 1940s, the Japanese naturally turned to washi (Japanese handmade paper) because it was well known for its strength and versatility in a wide variety of applications. Subsequent research showed that paper made from kozo and mitsumata fiber could be used to make a very serviceable balloon. Mikesh indicates that once production was underway a machine-made paper was developed and utilized, but there is no question that the early balloons and thousands of the 9,000 balloons eventually deployed to America were made from 100 percent handmade paper. Hundreds of papermakers in famous washi-producing areas all over Japan were put to work fabricating the required paper. During my 1975–1977 research on Japanese papermaking I came eerily close to the balloon bomb story. I found that many of the craftspeople I was learning from remembered making paper for the balloon bombs, though few of them knew what they were contributing to at the time. Many laughed when I brought up the subject, and I had the feeling they were embarrassed or maybe ashamed about having contributed to the effort. But when they could tell that my interest was sincere, they spoke seriously of the heavy production demanded by the military government at the time. "Yes, I sure do remember making that paper," one papermaker told me. "I think I still have a few sheets of it tucked away somewhere. All we did for months and months, day in, day out, was make that paper. And all we had to eat were potatoes, because they sent all the rice to the soldiers." Another craftsman said, "That paper was incredibly thin. I remember we used it to re-cover the shoji (sliding partitions), and it was so thin you could see the ridges of the distant hills right through it." According to Mikesh, the handmade sheets for balloon manufacture weighed about 15 grams per square meter. At various assembly locations the paper was laminated alternately with and against the grain, three or four layers thick, with an adhesive made from a type of Japanese potato called konnyaku (Amorphophalus konjac K. Koch). Blue colorant was added to the paste so that, once laminated, the sheets could be checked over a light table for non-uniformity of paste application or any other defects that might permit the escape of gas. To keep the paper from cracking and hardening in severe high-altitude temperatures, the paper was softened by dipping it in a solution of soda ash, a water wash, and then a solution of glycerin. The glycerin wash was soon replaced with calcium chloride and other softeners because the glycerin was more urgently needed for munitions powder. After drying, 600 carefully cut pieces were pasted together to make each final balloon. Much of the assembly work was performed by high-school girls specially trained to glue the seams. After a 24-hour test for air leakage the entire balloon was coated with a waterproof lacquer manufactured by the Nippon Paint Company (ingredients: butyl alcohol, benzol, triphenyl phosphate, dibutyl phthalate, butyl acetate, ethyl acetate, acetone, and nitrocellulose). The finished product was not only lightweight and strong but it had only one-tenth the hydrogen gas permeability of the ordinary, rubberized balloon fabric in use at the time. The second critical design problem facing military researchers was that each balloon had to automatically keep itself within the altitude range of 30,000 to 38,000 feet where the high-speed winds blow eastward. The problem was complicated by the unavoidable, Archival photographs of the Alturas balloon, discovered drifting over Crater Lake, Oregon, on January 10, 1945. A P-38 Lightning was dispatched to shoot it down, but the balloon continued to drift until it finally caught in a tree a mile northeast of Happy Camp Lookout in the Modoc National Forest. The balloon was shipped to Moffett Field, patched up, re-inflated, and flight-tested. Courtesy of Moffett Field Museum, Moffett Field, California. summer 2006 - gradual escape of varying amounts of gas and the drastic changes in temperature from day to night. Altitude stabilization was eventually accomplished by fitting each balloon with a suspended, castaluminum ring loaded with 32 sand-filled ballast bags in addition to its bombs.2 The ballast bags added an extra 200 pounds to the payload but they were wired to a battery-powered altitude control device that automatically fired explosive pins and dropped two bags at a set minimum altitude to keep the balloon at the correct height as it drifted toward North America. A gas relief valve was set to release gas when pressure increased during sunlit daytime hours. The final payload of incendiary and antipersonnel bombs was released on anybody or anything below and the balloon envelope and apparatus were then destroyed by separate, fused explosive charges, in theory destroying all evidence. The entire system had to function at jet-stream-altitude temperatures as low as minus 50 degrees Celsius (58 below zero degrees Fahrenheit). During the war, American security imposed a news blackout on any balloon-related stories, and in the spring of 1945, disruption of supplies in Japan and a lack of reports of successful crossings put a halt to the project. Only an estimated 1,000, of a total of 9,000 balloons sent, actually completed the crossing, but Mikesh's maps and tables show the balloons made it as far north as the Aleutian Islands, as far south as Mexico, and as far east as Michigan. A balloon caused the only enemy action deaths on the American mainland during the entire war when six people found a downed balloon and attempted to drag it out of the woods. In addition, a balloon came down and cut power serving a building in Hanford, Washington, where the Nagasaki plutonium was being made. But beyond these events, other than a few minor forest fires, the balloons did very little damage. Mikesh concludes that 1978 drawing by Richard Flavin based on a similar image from Mikesh publication. The drawing was first printed in Nagashizuki: The Japanese Craft of Papermaking (Bird and Bull Press, 1979); and subsequently appeared in Japanese Papermaking: Traditions, Tools and Techniques (Weatherhill, 1983), and various reprints of same. Courtesy of the author. 10 - hand papermaking the "free balloons" were a military failure because their ultimate destination could not be controlled. But in my view, if the balloons had been sent in larger numbers, and especially if they had carried the germ warfare bombs being developed and deployed by the Japanese in China,3 their potential for causing harm, fear, and confusion would have been much greater. In the end, the story very likely represents the most massive handmade paper production effort ever undertaken for a single use. And it is perhaps the ultimate testimony to the tremendous versatility of Japanese handmade paper. Afterthoughts In the epilogue to his book, Mikesh describes a 1955 find of a balloon and live bombs in Alaska, and warns anyone finding anything even faintly resembling a balloon and its parts to inform local authorities immediately. While the chance of finding unexploded but still lethal bombs is unlikely I would add that an inspection of Mikesh's maps of North America shows a concentration of found balloons or parts that correspond with his Japan-to-North America jet stream map shown earlier in the book. The combination suggests that any new finds may be more likely in the Northwest of America and the Southwest of Canada. Wilderness hunters, hikers, and campers should beware. Additional aspects of the story are worthy of the reader's attention. For an intriguing description of how the sand used in the balloon ballast bags allowed the Americans to pinpoint one of the balloon launch sites (and subsequently bomb it toward the end of the war) see the "Balloons of War" section in John McPhee's January 1996 article in The New Yorker.4 Liam Callanan's June 2004 essay in Slate relates the WWII American government news blackout on the balloon bombs to the current paucity of information on what is really happening in Iraq. He also gives details on the six people who were killed in May of 1945 after finding a downed balloon.5 A bibliography of websites on the topic can be found at http://www .lib.msu.edu/unsworth/genhist/ww2/ww2st/fugo1.htm. ___________ notes 1. This essay and my shorter discussion of balloon bombs in Japanese Papermaking: Traditions, Tools and Techniques (Tokyo: John Weatherhill, Inc., 1983; Warren, CT: Floating World Editions, 2005, revised edition) draw heavily from Robert C. Mikesh's detailed and authoritative work Japan's World War II Balloon Bomb Attacks on North America (Smithsonian Annals of Flight, no. 9, Washington, DC: National Air and Space Museum, Smithsonian Institution, 1973). Mikesh's book, based on 10 years of research, contains photographs, tables, charts, maps, and wiring diagrams. It is required reading for anyone interested in the topic. This book is available from the National Book Network. Call 800-462-6420 and provide the book's ISBN: 0-874740911. 2. In fact, the altitude control and bomb-dropping mechanism was worked out concurrently with the development of the paper balloon envelope. 3. "Biological Weapons Program" from the website of the Federation of American Scientists. Retrieved January 4, 2006 from http://www.fas.org/nuke/ guide/japan/bw/. 4. John McPhee, "Annals of Crime, The Gravel Page," The New Yorker, January 29, 1996, 52–60. 5. Liam Callanan, "Censorship's Trial Balloons: What happens when wartime news gets censored?" posted June 16, 2004 on Slate online magazine. Retrieved January 4, 2006 from http://www.slate.com/id/2102499/. Archival photograph of the re-inflation of the Alturas balloon. Courtesy of Moffett Field Museum, Moffett Field, California.