I was really too small back then (in the ‘60s) to know what was going on what. I remember when Roundup came on the market in the ‘70s as something of a scary-miracle herbicide, however.
I think Round Up is 2-4-D and IIRC Agent-Orange is 2-4-5T.
AO was used for killing the woody plants 2-4-D won’t even phase.