WWII records are more readily available. I’ve found draft registrations for the first world war for all four great grandfathers and for the second two. I think after the age of 60, you no longer had to register for the draft. As my dad’s grandfathers were quite a bit older than my mom’s ergo no WWII draft registration for them. It’s too bad since the WWII ones are a little more detailed. They actually include a height and weight. It’s how I found out that I would tower over my great grandfather, only 5’4.