Apollo 11 when I was five, the actual walk on the moon. I was ossified in front of the TV as it was happening, and it turned me into a space geek for life.
I have vague memories of stories about Vietnam on the nightly news that my dad always watched before that, but can't remember any specific events from that, just the name 'Vietnam'. My dad's habit of watching the nightly news became my habit pretty quickly and was fully ingrained by the time I was 10 years old. I very distinctly remember watching the news the day Saigon fell, including seeing on a broadcast the iconic photo of the helicopter on the roof of the US embassy with the long line of people waiting to get on. That one really affected me (the whole story, not just the photo), seeing a country fall to communism like that since my mother and her family defected from East Germany when she was a kid. I knew what the losers were in for.