How Britain Beat Germany’s Magnetic Sea Mines
medium.com
medium.com
Only through the absolute luck of a Luftwaffe plane ditching its cargo prematurely, the contact switch not being set, and the salt water not self-priming the mine because the air-dropped mine lands in a swamp does the United Kingdom short-cut research / spying efforts and address the magnetic sea mines.
The countermeasure tests being done through live tests must have been fun to volunteer for: "Take this plane, fly 35 feet off the water and when the mine goes off the blast will shoot you into the air."
One handy trick if your historical source photo is just too small is to resize and then apply a halftone effect - at least the analog-type distortion is consistent with that of newspapers, textbooks etc.
Interesting read for sure!