The A-10 was designed in part by an exNazi pulot who was known for expertise in attacking ground targets.
An Israeli F-15 once collided with another plane. The other plane was destroyed, but the F-15 flew back to base and landed safely. Everyone was shocked when they realized the whole right wing was gone.
During WWII, the Nazis had sarin and tabun nerve gas. They assumed the Allies had it too, so they never used it. As the Allies were advancing through Germany, they were shocked and horrified with the nerve agents they discovered.
During D-Day, the Allies were not prepared for chemical warfare. If there had been just a light sprinkling of gas, they would have went right back to the water.
At the beginning of WWII, the Axis and Allies agreed to no use of gas. The British were prepared to drench Nazi forces in gas, mainly mustard, if they invaded England. Most of the gas was made in America.
Mustard gas only killed about 3% of affected soldiers.
America still has a massive gas supply, for "disposal".
After WWII, a favorite way to destroy stocks of gas was to put it on ships, then sink the ships. Brilliant.
There are some places where biological weapons were tested that are still deadly and off limits decades later, even after attempts to decontaminate.
If you can't guess, I'm fascinated with Biological and Chemical Warfare (BCW)