He gifted pens (eye droppers of course) to Rough Riders in training at their Camp in Las Vegas, New Mexico. This was just prior to their departure to fight at "San Juan Hill" in Cuba. I suspect he wanted to make sure they had the ability to write home.
About twenty-five years ago I was fortunate to meet a granddaughter of one of the Rough Riders in Las Vegas. She had responded to an add I had plaaced in the local paper about my interest in purchasing fountain pens.
She had her grandfathers pen and had no interest in it - so, I purchased it. I wish I had taken more notes about the stories she told me about her grandfather - oh... hindsight.
I have photos somewhere and when located will post them here.
Thanks for posting the advertising poster & reminding me...