People used everything they could for their protection, from most primitive things like throwing rocks to more sophisticated kind of traps made with explosives, usually those kind of traps required knowledge so they were rare. People invented some traps or something like false traps, everything was allowed in order to keep yourself and your group safer.
Armies used mines of course, there were whole areas covered with mine fields, some urban areas also were covered with all different kind explosive things, booby traps.
In some areas where soldiers had open terrain in front of them, or terrain with bush, and if they planted mines there, they usually throw all kind of empty cans, like food cans or anything similar. As we understanded at that time they used that in order to confuse enemy if they coming during the night trough the mine field with mine detectors.
So basically if man going with those mine detectors trough bushes during the night and trying to discover mines digged in ground he is going to be confused with lots of false readings from all of the cans and metal garbage, so he is not going to pay good attention after some time.
Pretty soon lots of folks started to throw cans in areas that supposed to be dangerous, or hard to watch all the night.
Sounds stupid and primitive, but in most of the situation it is worked.
Whenewer during the night i was stuck in some area that suspiciously was covered with lot of empty cans, or other small metal garbage usually i tried to find another way, even i was sure in 90 % of situations it was only empty cans.
I would just turn back beliving that somebody set up a trap. When it comes to life or death even very small percentages count.
It was just so basic opinion in that time that in every mine field you gonna find lot of old cans to confuse mine detectors that we all belived in that.
In a SHTF scenario some signs of danger will become common, use them to your advantage.
What are your plans for home defense?