The Best Wood for World War I Airplanes

To manufacture thousands of airplanes for its World War I allies, the United States would fell acres of spruce.

America needed airplanes—lots of them.

It was the spring of 1917, and the United States was about to enter the Great War. Only a few hundred aircraft had been built since the Wright brothers’ inaugural flight at North Carolina’s Kitty Hawk in 1903. Now, the country was committed to darkening the skies in Europe with 12,000 sophisticated combat aircraft. To achieve such a goal, the U.S. Army desperately required blueprints, engines, fabric, glue, and countless other items large and small. What was needed most, though, was lumber—more than 100 million board-feet cut to exacting specifications. 

And not just any lumber. The best wood for the job was Sitka spruce, which grew in a narrow band of territory in the Pacific Northwest. Suddenly, spruce was regarded as among the most precious resources in the war effort. “If the Huns controlled the spruce supply of the world, they could control aerial warfare,” declared an article in the wartime Spokane Press. So began a project to fell trees, mill wood, and transport it across the country to jump-start a U.S. aviation industry that had barely gotten off the ground.

The Army’s Spruce Production Division (SPD) was in operation for just one year, on a distant fringe of the war effort. Yet at its height, the division employed nearly 30,000 U.S. soldiers, aided by 100,000 civilians, and it consumed some $45.5 million in federal funding (more than $1 billion in today’s currency). The project was responsible for buying huge tracts of timber, creating a union-like federation of timber workers, and building a complex network of railroads, both of which survived long after the war ended. The epic project represented an admirable coordination of military and civilian resources, akin to the Manhattan Project and Project Apollo in later decades, though more rustic.

That said, modern eyes gaze ambivalently at the program. Conservationists mourn the clear-cutting of enormous swaths of old-growth trees, while some historians fault government efforts to co-opt the labor movement by creating a large, Army-sponsored quasi-union. Yet, from the perspective of 1917, the need for spruce outweighed  other concerns.

 “No one realized, no one even dreamed that before this single item could be procured, an army must be sent to make war in the virgin forests, a vast industrial machine must be built up, and a great story of pluck and grit, of daring initiative and patient resourcefulness must be carved out,” wrote Cuthbert P. Stearns, who was an officer in the program, in his 1920 book, History of Spruce Production Division and United States Spruce Production Corporation. “It is a war story without the horror of devastated cities and of torn and bloodied men, and without the glamor that goes with victorious achievement upon the field of honor. And yet—this Northwest woods has become a field of honor; without the heroics, but not without the heroic.”

All spruced up

When World War I broke out, the airplane was still largely regarded as a record-setter, a stunt vehicle, an object of curiosity, a science experiment writ large—anything but a useful form of transportation or a weapon of war. Each one was hand-built, and no two were identical. Although the United States is the birthplace of powered flight, France would become the cradle of its early development. In 1906, 1907, and 1908, the French built more airplanes than the rest of the world combined.

Germany, however, was the first nation to fully embrace the military potential of the newfangled contraptions. From 1908 to 1913, Kaiser Wilhelm’s government spent $28 million on airplanes. France was second, at $22 million, Russia third, and Italy fourth. The United States was 14th behind Chile and Bulgaria.

In 1914, U.S. manufacturers built fewer than 100 airplanes. By 1916, even as the air war was raging in Europe, the U.S. military owned a grand total of 118 already-obsolete aircraft—less than half as many as the Royal Air Force lost in combat during a single month in 1917 (known as Bloody April). This failure of American imagination had its roots deep in a military culture that resisted technological change. “Mismanagement, neglect, and outright hostility by the Army toward military aviation sums it up in a nutshell,” says Chris Moore, a curator in the aeronautics department at the National Air and Space Museum. “The people who could have influenced aviation really didn’t try to make it work.”

The Army didn’t get around to buying and accepting its first airplane—a Wright Military Flyer—until 1909 (see “Wilbur and Orville’s 1909 Triumph,” Winter 2025). It was assigned to the aeronautical division of the U.S. Signal Corps, which had been created two years earlier and whose entire flying fleet consisted of a single dirigible. Army brass were skeptical about the potential of airplanes, so officers were permitted to serve in the division only on a temporary basis, and they were transferred back to their original units before they could accumulate much flying experience—which might partly explain why 13 of the 53 men trained as pilots died in fatal crashes.

As soldiers in World War I suffered the horrors of trench warfare, the dramatic aerial dogfights being fought overhead were unmistakable evidence that airplanes had a legitimate future in what modern military strategists call the battlespace. The National Defense Act of 1916 appropriated $13 million for the Signal Corps’ Aviation Section.

Then, in April 1917, President Woodrow Wilson declared war on Germany and its allies. The next month, he received a cable from Alexandre Ribot, the French prime minister. “It is desired that, in order to cooperate with the French aeronautics,” wrote Ribot, “the American government should adopt the following program: The formation of a Flying Corps of 4,500 aeroplanes to be sent to the French Front during the campaign of 1918. Two-thousand planes should be constructed each month as well as 4,000 engines, by the American factories. This is to say that during the first six months of 1918 16,500 aeroplanes (of the latest type) and 30,000 engines will have to be built.” 

Ribot’s request fell under the heading of promesse en l’air, which translates roughly as “ain’t gonna happen.” The U.S. didn’t have any combat-ready models in its portfolio, and even if it did, the homegrown aircraft industry didn’t have the expertise or capacity to pump out airplanes at such a prodigious rate. The Army eventually decided on a somewhat less ambitious plan to deliver 12,000 airplanes to Europe during the first half of 1918, in addition to building 5,000 trainers. To fund this program, the U.S. Congress passed the Aviation Act, which earmarked an impressive $640 million for military aviation, on top of the $10.8 million that had already been allotted before war was declared. A mere three years earlier, the Aviation Section had six airplanes and was budgeted at $125,000.

To gear up for manufacturing, the Army also formed a division devoted to nothing but supplying the war machine with lumber. And not just for domestic production. Now that the U.S. had finally ceased its isolationist stance and joined the fight, the French, British, and Italian air forces wanted to supplement the American lumber they’d been buying on the open market with even-higher-quality virgin wood that would be supplied as part of the Allied war effort. 

On average, about 1,000 board-feet of lumber went into a World War I airplane—out of which some 500 feet ended up as waste. The type of wood depended on what was available, what was affordable, and what purpose the particular component would play. “Basswood is good for ribs and cap strips because it is light, has a uniform structure, and can take a nail without splitting,” says Jay Flanagan, a restoration specialist and master woodworker at the National Air and Space Museum. “It’s best to use a hardwood for an area that’s going to be under a lot of compression, so ash or oak for where the landing gear gets bolted on. Ash, oak, poplar, and walnut steam-bend quite well so they were frequently used for curved parts.”

The Modified Standard J-1 biplane trainer that Flanagan restored at the Museum is a prime example of the whatever-works-best approach. “The fuselage longerons and struts were built of a mix of ash and spruce,” he says. “The engine bearers were white oak. The rib web of the wings —basically, the shape of the airfoil—that was basswood. The cap strips were basswood. The spars were spruce or Douglas fir. The wingtips were steam-bent poplar. So they just used the whole forest of American hardwoods and softwoods to build airplanes back then.”

But for aviation, the wood par excellence was a magnificent evergreen designated Picea sitchensis—Sitka spruce. Since wood is a natural material, a certain amount of unpredictability is factored into the engineering equations. Sitka spruce trees grow extremely tall—as high as 300 feet—and they’re almost perfectly straight, with long parallel cells that line up like a box of straws. Also, to capture sunlight in densely wooded forests, the canopy is limited to the very top of the tree, with hardly any growth below, leaving the Sitka trunks largely free of branches and knots. As a result, the wood they produce is extraordinarily uniform, and it can be milled into, say, 40-foot-long two-by-fours to serve as wing spars. “It’s almost a perfectly engineered material,” says Flanagan. “It’s not the lightest wood, and it’s not the strongest, but for its weight, it’s the best compromise. And it’s still kind of flexible, so it’s good for structural elements because it is less likely to split or shatter under load. Sitka spruce offers a happy medium.”

Sitka spruce is found almost exclusively in a narrow band nearly within sight of the Pacific coast. In the early years of the 20th century, it wasn’t prized for much of anything besides the majestic masts of sailing vessels. But as soon as airplane builders discovered it, they realized that Sitka spruce “checked all the right boxes,” as Flanagan puts it, and it was seen as almost mythical.

“Nothing takes the place of spruce for airplanes,” Frank Parker Stockbridge wrote in his laudatory 1920 history, Yankee Ingenuity in the War. “Other woods are as tough, but heavier; the difference in speed between a ’plane made of spruce and one of fir, for instance, on the same model is measured by miles per hour. Spruce is elastic, absorbing shocks instead of breaking under them. Clear, straight-grained spruce does not splinter when hit by a bullet; the missile passes through, leaving a clean, round hole that does not materially weaken the structure.”

Unfortunately, the demand for Sitka spruce far outstripped supply. When the war began, three million board-feet of Sitka spruce was being milled monthly. Of this, perhaps 10 percent was good enough to use in airplanes. With the U.S. preparing to join the war effort beyond its own borders, the production goal jumped to 10 million board-feet a month—later raised to one million board-feet a day. Not only did trees have to get cut, but then the wood had to be processed. Next, transportation to the mills and across the country had to be arranged. Complicating matters, the logging industry in the Pacific Northwest was in the middle of virulent labor unrest that had led to strikes being called by the Industrial Workers of the World (IWW). 

The Army assigned a logistical maven and organization man by the name of Brice P. Disque to oversee the logging operation. Although he “didn’t know a spruce tree from a white rhinoceros,” as one of his friends described him, Disque understood his mission. “To a soldier, in time of war, any means that are necessary are justifiable,” he wrote later. “I determined to ship the ten million feet at the earliest possible date, regardless of cost, or of whom it hurt, because by so doing I might assist in stopping the war one day earlier.”

Axes to grind

Brice Pursell Disque understood that you can’t always get what you want. But if you try sometimes, you’ll find you get what you need. As an 18-year-old clerk toiling in a grain store in Ohio, he wanted desperately to attend the U.S. Military Academy in West Point, New York. When a promised appointment fell through, he enlisted as a private in the Army in 1899. 

Dispatched to the Philippines, he distinguished himself in the brutal guerrilla war and was commissioned as a lieutenant two years later. He proved to be an elegant horseman and resourceful administrator, and he eventually earned a promotion to captain. But with no more wars to be fought, there wasn’t much opportunity for further advancement. Frustrated by the lack of prospects, he resigned his commission in 1916 to become warden of the Michigan State Prison. 

Disque’s timing couldn’t have been worse. When the U.S. entered the war a few months later, he immediately asked to be reinstated to active duty and assigned to a combat unit in France. He was crestfallen when General John J. Pershing, the commander of the American Expeditionary Forces, asked him instead to travel to the Pacific Northwest to evaluate the logging situation. When he returned to Washington, D.C., Disque recommended that timber companies, mill operators, and lumberjacks be brought together into a single Army organization working toward a common goal. The Spruce Production Division was formally established in September 1917, and Disque was recommissioned as a lieutenant colonel (later promoted to colonel) to run it. 

At the time, Disque was 38, a lean angular man with hair brushed back from a high forehead in the approved military style. He set up an office in downtown Portland, Oregon, in the Yeon Building, a 15-story skyscraper named after the timber tycoon who’d financed it, while an operations and training center was established at Vancouver Barracks, just north of the Columbia River in Washington. Then, he proceeded to create a model of vertical integration, from buying the land the trees grew on to delivering the processed wood to the railroads transporting it east.

Disque’s first task was to secure enough manpower to do the job. Although he had access to tens of thousands of soldiers capable of performing manual labor, Disque also needed skilled timbermen to work as fellers, buckers, hook tenders, chokermen, rigging slingers, and so on. That meant bringing civilians into the fold and having them work alongside enlisted men. During the previous summer, loggers in the Industrial Workers of the World, the strident union popularly known as the Wobblies, had gone on strike to force timber companies to agree to an eight-hour workday, higher wages, and upgraded working conditions. Disque responded by creating what was in effect an anti-union to compete with the IWW.

The Loyal Legion of Loggers and Lumbermen, known as the 4Ls, was created in fall of 1917. All soldiers and civilians were required to join the organization, as were the managers of the mills and campsites. As an inducement, the LLLL embraced most of the goals that had been sought by the Industrial Workers of the World, most notably the eight-hour workday. IWW leaders detested the 4Ls members, whom they mocked as “Little Loyalty and Large Loot,” dismissing the group as a government-run confederation of strikebreakers. “Army officers, adept in terrorism, with no gentlemanly scruples to hold them from any nefarious design, acted as organizers,” James Rowan, an IWW organizer known as Jesus of the Lumberjacks, wrote in his highly partisan memoir. 

The strike ended in March, when the timber barons agreed to an eight-hour workday. Although the IWW claimed credit for the victory, it probably had at least as much to do with the behind-the-scenes work Disque had done to market the 4Ls and its progressive labor program to reluctant leaders of the logging industry. Patriotism was one of the quasi-union’s major selling points. A color-drenched poster for the Spruce Production Division shows a lumberjack holding an axe with “LLLL” emblazoned on the head, and a caption that reads: “The strength of your blows and the loyalty of your hearts will win this war.”

The Spruce Production Division also won converts by raising wages and improving conditions in crude civilian-run logging camps. In addition, it built dozens of camps to military specifications—rustic by modern standards but positively deluxe at a time when 86 percent of Americans didn’t have access to running water. As one soldier wrote in a letter home: “We have an excellent camp here, which is clean and sanitary. We live in bunk houses built on car trucks, about sixty feet long and divided into three rooms each. There are ten men to each room. We have all the modern luxuries—steam heat, electric lights, hot and cold water, and last but by no means least, we have the very best eats on earth.”

Of course, chopping down trees was only one leg of the stool. A giant fleet of trucks was assembled to rumble along temporary roads to get the logs to designated mills, including three new facilities that had recently been built. The largest, the cut-up plant at Vancouver Barracks, was staffed by some 5,000 men working three eight-hour shifts a day. The Army also began building 13 railroads in Washington and Oregon—173 miles of main lines and 181 miles of spurs. At one point during the summer of 1918, 10,000 spruce soldiers were assigned to railroad construction.

By November 1918, the LLLL boasted more than 125,000 members. During the previous 12 months, the Spruce Production operation had delivered 143 million board-feet of aircraft-quality Sitka spruce and Douglas fir, which were used in both airplanes and ships. This was thanks in part to creative new milling techniques that cut the wastage rate from 90 percent to 40 percent. 

Special deliveries

The Allies had asked for 100 million board feet of lumber from the U.S. By the end of the war in November 1918, the Spruce Production Division had produced nearly 185 million board feet. This lumber was used in the manufacture of 16,952 airplanes: 11,754 by U.S. contractors, 4,881 in France, 258 in England, and 59 in Italy.

Among the aircraft produced were more than 4,346 De Havilland DH-4s, a British-designed two-seat, single-engine observation biplane and bomber. The U.S. chose the DH-4 because of its comparatively simple construction and because it was well-suited to the new American 400-horsepower Liberty V-12 engine. These U.S.-built DH-4s were dubbed the “Liberty Plane.” By war’s end, 13 Army Air Service squadrons, five of them bomber squadrons, were equipped with DH-4s. On May 11, 1918, the first DH-4 Liberty airplanes were delivered to France. Eventually, the U.S. would send 1,213 units to France, though only 696 reached the Zone of Advance into German territory. Still, they proved their worth during less than four months of combat. Of the six U.S. Medals of Honor awarded to aviators during the war, four were received by pilots and observers flying DH-4s. 

The war would also see the mass production of some 7,000 trainer aircraft, including 1,600 SJ-1s and over 4,000 units of the Curtiss JN-4D (popularly known as the Jenny), which were used to train more than 90 percent of U.S. pilots during World War I. The need for advanced trainers also led to the development of the JN-4H, powered by a 150-hp Wright-Martin-built Hispano-Suiza engine in place of the 90-hp Curtiss OX-5. More than 400 JN-4H aircraft and purpose-built variants were made with spruce harvested in the Pacific Northwest. 

Back home, the day after Germany surrendered, the Spruce Production Division’s logging operations abruptly ceased. It took longer to unwind the rest of the organization. A few of the rapidly built railroad lines were bought by logging companies. Later, $12 million in goods would be auctioned off in the largest government sale since the construction of the Panama Canal was completed in 1914. The LLLL continued to exist, but its management-friendly politics were a millstone around its neck. “By the early thirties the once great Loyal Legion was a pitiful remnant,” history professor Harold M. Hyman wrote in his 1965 book, Soldiers and Spruce: Origins of the Loyal Legion of Loggers and Lumberman. “It was dead by mid-decade.” 

The U.S. government, meanwhile, had a plenteous number of surplus aircraft on its hands. Hundreds of JN-4s were sold to civilians, and the airplane soon became the mainstay of barnstorming pilots of the 1920s. The DH-4s proved to be reliable workhorses and were used as cropdusters and air ambulances. Notably, the DH-4 was the principal aircraft used by the U.S. government when air mail service began in 1918. Says the Museum’s Chris Moore: “The resulting glut of aircraft would serve to depress the aviation industry, which found no market for more expensive new designs. It was cheaper to modify surplus aircraft than to design from scratch. But the many cheap surplus aircraft also allowed many individuals who could not afford a brand-new aircraft to be able to enter aviation. These barnstormers brought the airplane to many people who would otherwise not have experienced flight. Even though for most people an aircraft was still an uncommon sight, barnstormers and early air transport pilots, flying their war surplus aircraft, brought aviation to America and fueled the growing air-mindedness that dominated the 1920s and ’30s.”

Although the thousands of soldiers stationed in U.S. forests had gone home, the Spruce Production Division’s legacy was felt years afterward as it aided the rise of Boeing—which had been founded in Seattle in 1916—and it sped the industrialization of the local logging industry. The division’s soldiers themselves were gifted with commemorative books, featuring a photo of a DH-4 Liberty with the caption: “Quantity production of this and other models of aircraft furnished eyes for our armies and bombing facilities to annihilate the enemy, all of which was made possible only by the gigantic efforts of the Spruce Production Division, United States Army.” 

A former daily newspaper reporter, Preston Lerner is a frequent contributor to Air & Space Quarterly.

This article, originally titled “The Tree That Built an Air Force,” is from the Spring 2025 issue of Air & Space Quarterly, the National Air and Space Museum's signature magazine that explores topics in aviation and space, from the earliest moments of flight to today. Explore the full issue.

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