We never locked our house until 1969, nor did anyone else on our secluded block. Then, a divorced woman who lived with her 3 sons was attacked inside of her house when she was home alone, and two houses were burglarized, all in the same summer. I remember most of the people on the block then started locking their houses, and many, including us, got a dog. I remember my parents giving me a house key and I'd wear it on a chain around my neck with my St. Christopher medal. We kept the doors unlocked if more than 1 of us were home, however, if we were home alone, we were to keep the house locked. However, especially in summer, we'd just lock the screen doors, which, of course is about zero deterrent to a bad guy.
Anyhow, I remember twice someone trying to get into the house when we were home. Once during a power outage. My dad snuck out of the house and came up behind the guy. We all watched it, as the house had floor to ceiling glass 1/2 of the way around it. It was darker inside than outside, so he couldn't see in but we could see out. He was walking around the house trying all the doors. At the last second he saw my dad across a corner of the living room. My dad was huge!
6' 3" 230# WWII combat engineering vet with a .45 1911 coming at you in the rain! YIKES! He ran!

My dad chased him about 2 blocks before he finally got away. He came back in holding that gun, soaking wet, and said "He got away gosh dang it." Then he called the cops. I asked him why he didn't shoot the guy? He said because he didn't have to. I was about 6-7 years old, as I recall. We got the dog shortly after.