American History

I was just reading about proximity fuses the US developed for AA artillery. Don’t know if it went down to 3” size. For awhile they wouldn’t let the army use them because they were afraid the nazis would collect a dud and figure out how to make them so for a long time only the navy could use them. They were first used, to dramatic effect, during the battle of the bulge. They’d set the artillery to air burst above German soldiers who were afraid to get out of their Fox holes.