Pre-WWII staged attack levels ‘Cardboard City’ Blown away
Published 5:32 pm Tuesday, May 19, 2026
It went off with a bang.
A month before the Japanese attacked Pearl Harbor, Louisiana began construction for a plant that would help America win World War II by staging a simulated invasion on “Cardboard City.”
Fifteen mock buildings were destroyed at the Missouri Ordinance Works, now the site of Dyno Nobel along Highway 79 at the south edge of Louisiana.
The idea was novel, but fitting. The plant would make explosives for the military.
Popular Mechanics magazine dryly said the facility had substituted “gunfire and dynamite for the conventional formalities usually performed with a spade.”
Perhaps the most dramatic description was offered by Associated Press reporter Henry B. Jameson, who touched upon concerns about the threat posed by America’s potential enemies.
“The inevitable fate of an unprotected village caught in the path of a modern war machine was vividly portrayed today in a simulated infantry and artillery attack on a cardboard city that was blown up in 30 minutes,” Jameson wrote.
The edifices looked like something from a movie set, with different shapes, styles and designs. There was a courthouse, skyscraper, church, stores and homes measuring eight to 16 feet tall and eight to 12 feet wide.
Since spectators were to be kept a quarter-mile away during the invasion, girls from the National Youth Association volunteered to add bright paint so that the structures stood out.
The groundbreaking was set for 2 p.m. Sunday, Nov. 9. The explosions were to start at 3. The Louisiana Chamber of Commerce sponsored a parade before the ceremony, with the procession led by former governor and hometown nursery owner Lloyd Stark, who had lost a U.S. Senate primary the year before to incumbent Harry Truman.
Local leaders had hoped to bring in tanks and fighter planes, but had to settle for several 75 mm guns and 300 soldiers from a Fort Leonard Wood artillery brigade.
“As they fired, red flares and smoke bombs indicated hits or misses,” Jameson told readers. “When a direct hit was scored, the shell-like structures were blown high into the sky.”
Ten thousand people turned out, despite sub-freezing temperatures and a chilly wind. The “peaceful valley” in which the attack took place “was a virtual quagmire as a result of recent snow and rains,” Jameson wrote. Soldiers attacked from three sides and got practical experience in foul-weather training.
The main speaker was Frederick Muhlenberg, a highly-decorated World War I veteran who was with the Army Corps of Engineers. The Corps contracted with Hercules Powder Company to build the $20 million plant (more than $638 million today) covering 620 acres.
The lieutenant colonel told the crowd the Louisiana facility was “a most important link in the chain of national defense” and that America must be ready if war came.
“It is a vital necessity,” he said. “The country will be defended, cost what it may. If we fail in preparedness today, we fall tomorrow.”
Muhlenberg, a Republican who later followed six relatives in congressional service and retired from his architectural firm a week after turning 90, also addressed national divisions, especially those between workers and manufacturers – an issue of contention coming out of the Great Depression.
“Whatever may be the differences between employers and employees, or between labor organizations, they are all on one side, while Hitler is on the other,” he said, adding that Americans’ “love of country must not in this national crisis be sabotaged by any opportunist.”
The plant provided hundreds of jobs during the war, sometimes bringing three shifts of workers by train from Hannibal to meet demand. The closest Nazis ever got to invading Louisiana was a prisoner of war camp near what is now the intersection of 15th and North Carolina. After the surrender of Germany and Japan, the facility made fertilizer, agricultural products and other chemicals.
Hercules took full control of the plant from the government in 1954. The company merged with Ashland Inc. in 2008 and the facility later was acquired by Dyno Nobel’s parent company, Incitec Pivot Limited
The Louisiana Area Historical Museum has a room dedicated to Hercules, The collection includes a book about the company entitled “Labors of a Modern Hercules” by Davis Dyer and David B. Sicilia.
