Help me find book series

So I’m trying to remember this comic book series. It starts with a parent figure I believe telling these two kids their family tree and all the amazing stories they have. With the one I remember having a mustache colored guy. He’s in a war with two buddies of his. And this happened back in the 1900s. They get attacked by guys with swords and head to a cave. While doing so they lose some people. And at the end of the book he’s trying to snipe these people from a long distance. I’m sorry I can’t give more info but this is pretty much everything I remember.