Did you know: chainsaws were invented in 1780 to assist in childbirth? Then it replaced the bone saw during amputations. It wasn’t until later people figured out it’d work pretty good on wood.
I will explain but it’s going to get gross and gory. Warning if you don’t like discussions of childbirth trauma or general medical squeamishness. Don’t worry, I won’t include photos of any gore.

The Creation: To Assist with Childbirth
Before 1830, the cesarean section (aka C-sections) were not yet discovered so all babies had to pass through the birth canal…by any means necessary.
In the 1700s, when babies were turned the wrong way or too big to pass through, doctors had to cut bone and cartilage away to make room to allow passage.
This procedure was known as a symphysiotomy, and was performed by hand with a small knife and saw. Women suffered this without any anesthesia, as it wasn’t commonly used by doctors until 1846. So not only were women dealing with the pain of childbirth, they were also getting hacked up by their doctor.
It was a really inefficient process as it took a while for doctors to cut through everything they needed to by hand. So in 1780, two doctors invented the chainsaw to remove parts of the pelvic bone quicker. Still without any anesthesia though.

The medical chainsaw is much smaller than what we use today to cut down trees. The chainsaw was operated by a hand crank until the invention of the gasoline-powered one in 1926 (don’t worry, that one wasn’t used for medical purposes!).
Soon other doctors learned of this new invention and adopted it for general amputations. Previously, amputations were very slow ordeals, with the surgeon sawing through the limb for quite a while. Also, and I cannot stress this enough, without anesthesia.
Chainsaws Today
Today the symphysiotomy is no longer performed in the United States. However, it is still used in less developed countries where an operating room for a C-section is not available.
The modern chainsaw, as we now know it, developed slowly. Many variations of hand-cranked saws were used in the 1800s by loggers. In 1926, German mechanical engineer, Andreas Stihl patented the “Cutoff Chain Saw for Electric Power.” In 1929, Stihl patented the first gasoline-powered chainsaw called the “Tree-Felling Machine.”
Although powered by gasoline, the chainsaw of 1926 weighed 139 pounds and required multiple people to operate.

In 1945, at the end of World War II, the development of aluminum alloys and forged steel parts leads to one-person saws.
Sources:
Green, Amanda. “A Brief History of the Chainsaw.” Popular Mechanics. October 12, 2012. https://www.popularmechanics.com/home/tools/reviews/a8162/a-brief-history-of-the-chain-saw-13626055/ (accessed April 15, 2020).
Stihl Incorporated. “Stihl History: 1920s.” https://history.stihl.com/1926-1929.aspx (accessed April 15, 2020).
Marulli, Larissa. “Chainsaws were originally invented for helping with childbirth, not for cutting wood.” Business Insider. June 25, 2018. (accessed April 15, 2020).
“History of Anesthesia.” Wood Library Museum. https://www.woodlibrarymuseum.org/history-of-anesthesia/ (accessed April 15, 2020).