The Murderously Helpful Blowfly
During one of the bloodiest conflicts on American soil - the Civil War - perceptive strategists used disease as a weapon. They did so without knowledge of pathogenic bacteria and their insect vectors.
Diarrhea, malaria, yellow fever, and typhoid fever were decisive forces during the Civil War. Many battles were delayed, or avoided altogether when soldiers of both sides were too sick to fight. More than 1.7 million cases of diarrhea with 44-thousand deaths, and 1.3 million cases of malaria with 10-thousand fatalities were reported for the Union troops. The Confederates didn’t fare any better.
Human excrements, animal dung and dead life stock littered the camps, creating a cozy atmosphere for blowflies and enteric disease. Observant doctors noticed the benefits of maggots wiggling about in infected wounds and feasting on the dead flesh. Dr. Jones, a Confederate medical officer reported, "I have frequently seen neglected wounds ... filled with maggots ... as far as my experience extends, these worms eat only dead tissues, and do not injure specifically the well parts." Another medical officer of the Confederacy, Dr J.F. Zacharias, was the first to use maggots for healing wounds, "Maggots ... in a single day would clean a wound much better than any agents we had at our command ... I am sure I saved many lives by their use."
But the magic the maggots performed was minimal compared to the deaths caused by their adult counterparts. Simply by doing what every fly does during the day - feeding off refuse heaps and excrement puddles and then taking a nap in a soldiers face - the blowfly express spread pathogens quickly.
There was little that helped a soldier during bouts of diarrhea. Malaria, on the other hand, had a remedy. And it was used in great amounts. The Union troops reportedly consumed more than 19 tons of quinine during the Civil War and few things were as lucrative to smuggle as this medicine.
The connection between mosquitoes and malaria (as well as yellow fever) wasn’t clear at that time. Yet, several strategists knew that avoiding a battle against disease would help to win a battle against humans.
General Winfield’s losses during the march to Mexico City in 1847 were minimized by simply avoiding the hot summer, when mosquitoes would be most pestering. Fifteen years later, General Scott called for the “Anaconda constrictor” campaign in November, after “the return of frosts to kill the virus of malignant fevers below Memphis”.
During the Union’s peninsular campaign of 1862, General Joseph E. Johnston used disease to weaken his enemies, by forcing them to remain in the swamps. His superiors, not understanding Johnston's tactics, criticized him for twiddling his thumbs. He replied “I am fighting, sir, every day! Is it nothing that I compel the enemy to inhabit the swamps, like frogs, and lessen their strength every hour, without firing a shot?”
Johnston knew that a sick soldier requires all kinds of things, from doctors over medicine to food and transportation, thus weakening the infrastructure around him. A dead soldier merely needs a box, if at all. Twice outnumbered, Johnston allied with mosquitoes to win a battle.
It took the Union troops until summer to fully realize their enemy’s strategy. On July 4th, the Union forces were close to collapsing. The medical director Jonathan Letterman reported “after about 6,000 had been sent away on transports, 12,795 remained” and at least one-fifth of these men were sick.
Only 2 weeks later, another 7,000 soldiers were sent to rear. Reinforcements put the numbers of Union soldiers to 20,000. Mosquitoes and flies grinned happily over so much new fodder. By August, the Union lost one regiment a day to disease and the army of the Potomac was ordered to withdraw.